6,464 research outputs found
Body Talk: Male Athletes Reflect on Sport, Injury, and Pain
This paper examines how participation in physically demanding sport, with its potential and actual injurious outcomes, both challenges and reinforces dominant notions of masculinity. Data from 16 in-depth interviews with former and current Canadian adult male athletes indicate that sport practices privileging forceful notions of masculinity are highly valued, and that serious injury is framed as a masculinizing experience. It is argued that a generally unreflexive approach to past disablement is an extraordinary domain feature of contemporary sport. The risks associated with violent sport appear to go relatively unquestioned by men who have suffered debilitating injury and whose daily lives are marked by physical constraints and pain
WHEAT-IMPORTING STATE TRADING ENTERPRISES: IMPACTS ON THE WORLD WHEAT MARKET
The U.S. is seeking further disciplines on STEs in upcoming WTO negotiations on agriculture. The prevalence and reform of state trading among wheat importers is examined. Behavior investigated across countries and over time includes domestic price stabilization, world price transmission, import levels and sources, and grain quality.International Relations/Trade,
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Mitigating orbital debris in LEO with high power pulsed laser
There is a large amount of space debris in the size range of 1 to 10 cm that is orbiting the Earth at a very high velocity which could do tremendous damage to any space mission if it were to collide. This orbital debris has been generated from collision events between objects and fragmentations of objects in Earth orbits. The problem is that the amount of space debris is increasing exponentially with every major collision in space. To limit the probability of this happening, the rate of growth of space debris in orbit is being reduced through various design techniques employed in new space missions. However, the orbital debris already in space will require to be mitigated as well because in some of the bands, such as Low Earth Orbit (LEO), the density of space debris is very high. It is posing a threat to any operational satellite in orbit and the safety of spacecraft flights LEO is rather urgent.
The technique of using high power pulsed lasers on the ground has been viewed as the most feasible method to mitigate small space junk in the LEO band. It is one of the most viable solutions to mitigate the existing space debris in LEO. However, in order to design an effective orbital debris removal technique, the first logical step would be to gather as much information as possible on space debris that is known to exist within the orbital band of interest, like the two-line element of the space debris and its materials. This will help assess the design of the laser beam system and help give a more accurate picture of this de-orbiting strategy.
The objective of this poster is to provide a summary of the developed novel techniques for this de-orbiting model. It also presents the calculation and simulation of the required power that is necessary for the laser beam in order to slow down the orbital velocity of the space debris and also reduce its perigee. Reducing the space debris altitude by the amount necessary will significantly reduce its lifetime in Earth orbit and eventually cause it to re-enter the atmosphere where it will burn up
LDEF Materials Workshop 1991, part 2
The LDEF Materials Workshop 1991 was a follow-on to the Materials Sessions at the First LDEF Post-Retrieval Symposium held in Kissimmee, Florida, June 1991. The workshop comprised a series of technical sessions on materials themes, followed by theme panel meetings. Themes included materials, environmental parameters, and data bases; contamination; thermal control and protective coating and surface treatments; polymers and films; polymer matrix composites; metals, ceramics, and optical materials; lubricants adhesives, seals, fasteners, solar cells, and batteries. This document continues the LDEF Space Environmental Effects on Materials Special Investigation Group (MSIG) pursuit to investigate the effects of LEO exposure on materials which were not originally planned to be test specimens. Papers from the technical sessions are presented
LDEF thermal control coatings post-flight analysis
The NASA Long Duration Exposure Facility (LDEF) provided a unique flight opportunity for conducting experiments in space and return of these experiments to Earth for laboratory evaluation. The results of one of these experiments, S0010, Exposure of Spacecraft Coatings, in which selected spacecraft thermal control coatings were exposed to the low-Earth orbital (LEO) environment on LDEF are reported. The objective of the experiment is to evaluate the response of thermal control coatings to LEO exposure, which includes atomic oxygen, ultraviolet and particulate radiation, meteoroid and debris, vacuum, and temperature cycling
An improved background segmentation method for ghost removals
With ongoing research assessment in higher education and the introduction of master’s‐level work in initial teacher education, the growing need for teacher educators to develop research identities is discussed in relation to mentoring and support in two universities. Twelve interviews—with three teacher educators and three research mentors from each university—were carried out, in order to identify effective mentoring practices and other forms of support, as well as any barriers or problems encountered in developing a research profile. An innovative aspect of the methodological approach is that beginning researchers from the teacher education faculty in both universities undertook the interviewing and co‐authored the article. The need for an entitlement to and protection of research time is stressed, as well as a range of supportive practices within an active research culture. It is argued that this aspect of teacher educators’ professional development requires as much attention as the pedagogical aspects of their rol
An analysis of LDEF-exposed silvered FEP teflon thermal blanket material
The characterization of selected silvered fluorinated ethylene propylene (FEP) teflon thermal blanket material which received 5 years and 9 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. X-ray photoelectron spectroscopy, infrared, and thermal analyses did not detect a significant change at the molecular level as the result of this exposure. However, various microscopic analyses revealed a roughening of the coating surface due to atomic oxygen erosion which resulted in some materials changing from specular reflectors of visible radiation to diffuse reflectors. The potential effect of silicon-containing molecular contamination on these materials is addressed
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Propagation of Bessel beam for ground-to-space applications
We model the propagation of Gaussian and Bessel beams from ground through 22km altitude of atmospheric turbulence. We observe the Bessel beam has better performance based on
RMS intensity error and the captured beam powe
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LEO space debris mitigation using laser ablation
Since the first spacecraft was launched in 1957 a great number of spacecraft have been put into orbit and a significant fraction of these are still orbiting the Earth as inert vehicles or space debris. Major collision events between large satellites in Earth orbits have broken-up spacecraft systems for about half century; this has created a massive quantity of space junk – most of which are small particles. The number and quantity of debris items is increasing and as a result the probability of catastrophic collisions is growing progressively.
Objects in space, whatever their size, are potentially hazardous and can cause considerable damage, which may disable a space system and producing numerous secondary fragments as a result. Low Earth Orbit (LEO) requires particular attention because this band contains large masses of material orbiting at high relative velocities, up to 14 km/s. At this hypervelocity, even small debris, 5-10 cm, can produce extensive damage to any operation satellite and destroy any small satellites. Collision with smaller debris, 1-5 cm, could disable any space system. Therefore, our space assets in LEO are threatened by this large quantity of space junk, which may lead to collision cascading in the future.
Small orbital debris stays in LEO for a very long time (100s years) before re-entering the atmosphere, so it poses a great threat to any operational spacecraft. However, the debris lifetime can be reduced significantly by slowing the debris velocity slightly and lowering its perigee. This can be achieved by using the unique property of laser propulsion to generate thrust remotely on the orbital debris by beaming the necessary power from the ground. So, this paper assesses and simulates the engagement of laser beam pulses with space debris. It also calculates and simulates the required time and number of interactions for de-orbit and also simulates the required change in orbital velocity (∆V) of the debris to lower its altitude and cause it to change orbit and eventually fall into the upper atmosphere, where it will burn up.
In conclusion, space debris mitigation is now essential to protect existing space systems and maintain the sustainable use of outer space. That is why the space debris problem is now a very significant environmental issue. As this technique does not require launching space vehicles, we believe that this clearing strategy is an achievable and cost effective method to deflect and mitigate the effect of space debris
PHACT: parallel HOG and correlation tracking
Histogram of Oriented Gradients (HOG) based methods for the detection of humans have become one of the most reliable methods of detecting pedestrians with a single passive imaging camera. However, they are not 100 percent reliable. This paper presents an improved tracker for the monitoring of pedestrians within images. The Parallel HOG and Correlation Tracking (PHACT) algorithm utilises self learning to overcome the drifting problem. A detection algorithm that utilises HOG features runs in parallel to an adaptive and stateful correlator. The combination of both acting in a cascade provides a much more robust tracker than the two components separately could produce. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
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