Dissertations / Theses on the topic 'Radiation in the perioperative environment'
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Berry, Judith. "Pressure ulcer prevention in the perioperative environment." Title page, table of contents and overview only, 2004. http://hdl.handle.net/2440/37709.
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There are many terms used to describe pressure ulcers: pressure sores, decubitus ulcers, bedsores, and pressure necrosis or ischaemic ulcers. Essentially they all describe damage to the patient's skin and underlying tissue. The nursing literature abounds with information about the risk, grading, prevention and treatment of pressure ulcers. These ulcers are a problem in hospital and long term care facilities, and are a major cause of morbidity. In the hospital setting they contribute to an extended length of stay and by doing so 'block' the bed for use by another patient. The ulcers are difficult to treat, are an ongoing cause for pain and discomfort for the patient and can be a strain on hospital finances. Pressure ulcers are not unique to modern times, as they have been discovered on the remains of an Egyptian mummified body (Armstrong & Bortz 2001). This would suggest that the problem dates back to the Pharoahs, and has continued to be a challenging problem throughout the centuries (Bridel 1992). The escalating costs of treating these ulcers today, has brought about an emphasis on the risk factors, prevention and the appropriate interventions, rather than an acceptance of these ulcers as a tolerable ondition (Bridel 1992). In the operating room, nurses are faced with unique challenges when caring for their patients. This is due to difficulty in caring for patients under the influence of the anaesthesia required for surgery, long periods of forced immobility and the inability of the patient to perceive pain and discomfort from the pressure of the hard surface of the operating room table. These problems are increased by nurses' inability to gain access to the patient because of the sterile drapes required to cover the patient for surgery. Armstrong and Bortz (2001) present information from one study in which it is stated that surgical patients have 90% greater chance of developing pressure ulcers than medical patients. One reason for this may be due to the limited information available in regard to the most effective support surface to place on top of the operating room table. This gap in information is problematic for operating room nurses as it limits their ability to select the most effective item of equipment, and determine if the chosen equipment reduces pressure on tissue intra- operatively. The most effective operating room table mattress used and the skills and knowledge of the operating room nurse about the aetiology and prevention of pressure ulcer prevention, are important aspects of nursing care and can influence patient outcomes. The potential for complications to occur may be dependent on single or combined factors such as the patient's age, disease processes, nutritional status and mobility. Preparatory and supportive nursing interventions for surgical procedures based on best available evidence, nursing experience and patient preference, can reduce the incidence of pressure ulcer development in the perioperative environment. This doctoral portfolio contains four separate sections related and linked together by a common theme - pressure ulcer prevention in the perioperative environment. This first section of the portfolio situates the topic and provides a brief overview of the portfolio. The second section is a critical review of the literature pertaining to the most commonly used operating room table mattresses, and the effectiveness of these mattresses in the prevention of pressure ulcer development. This review highlighted a lack of quality research in this area, and while many evaluations have been undertaken to determine the effectiveness of perating room table mattresses, the results are contradictory concerning the patients, exposures and interventions. Because of issues related to the methodological quality of published research in this area a systematic review using meta- analysis was not possible rather a critical review of the research literature is used. The third section of the portfolio reports on a hermeneutic ethnography of the perceived skills and knowledge of nurses in the prevention of pressure ulcer development in the perioperative environment. This study was designed to determine if pressure ulcer prevention forms an aspect of the everyday practice of perioperative nurses. This review has highlighted the need for operating room nurses to review practices when caring for patients in the perioperative environment particularly in respect of pressure ulcer prevention. The fourth and final section of the portfolio summarises the research and provides recommendations for nursing practice and further research in the area of pressure ulcer prevention in the perioperative environment.Thesis (D.Nurs.)--Department of Clinical Nursing, 2004.
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Chadwick, Dorothy Lorraine. "What influences the practice of registered nurses in the perioperative environment? /." Thesis, University of Southampton, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582660.
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This study seeks to explore what influences the practice of Registered Nurses in the perioperative environment. The term perioperative care denotes care given to patients in anaesthetics, during the surgical procedure, and immediate recovery following surgery and is generally referred to as pre-, intra-, and post-operative care. The research design was a qualitative case study involving 10 registered practitioners in the specialty of perioperative care. Case study design was chosen because of its appropriateness for exploratory study. This research took place in a teaching hospital and the area of study consisted of six operating theatres. Data were collected over one calendar year. The study focused on Registered Nurses. In order to understand more completely factors that influenced these nurses senior medical staff, senior operating department practitioners and the educational coordinator were also included. Information was obtained through individual in-depth interviews with this sample, focus group discussion with the nurses, and the analysis of departmental documentation. Analysis of the data was undertaken by thematic framework analysis and the review of departmental documentation. Study participation was voluntary, with recruitment by self-selection. Findings highlighted a variety of influences guiding the practice of participants, showing both the similarities and differences in their choice of what was important to them. Discussions of the Focus Group were able to verify information gleaned from the in-depth interviews and the review of departmental documentation. Responses in relation to the understanding of the concept of evidence identified a knowledge gap within the specialty. In spite of exhortation of professional bodies and Government Directives regarding the use of evidence to support practice, it was not found to be greatly influential. Instead leadership, teamwork, culture, and communication were the most influential perspectives for the participants of the study. The results will be circulated widely to the practice and academic communities through publication in relevant journals. They will also be disseminated to the participants and related stakeholders, such as professional bodies of perioperative practice, in the form of an executive summary.
3
Wuttke, Sigrid. "Radiation conditions in an Antarctic environment." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975820451.
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Hill, Adam L. "NPS-SCAT CONOPS and Radiation Environment." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/7357.
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Solar cells are the primary energy-collection agents used onboard spacecraft converting energy from the sun into electricity. With solar cells being the main source of power for satellites, it is important to know how they operate and degrade when exposed to the harsh environment of low earth orbit. The objective of this thesis is to estimate the solar cell degradation that will be experienced on orbit due to radiation. This linked with the mission of the NPS-SCAT providing a quantitative measurement on orbit of how solar cells degrade over time can reduce risk of expensive national satellite by providing real-life solar cells exposure to threats of the space environment. A secondary goal of this thesis is to build and present a representation of the CONOPs (concept of operations) that describes the functionality expected on orbit. Coordination with the software programmers as well as the staff to set robust functionality is the goal for the CONOPs. This software package will be programmed into the two 1U flight certified CubeSats as their standard programming once implementation and testing have been completed.
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White, Ryan D. "A high-altitude nuclear environment simulation." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2315.
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Sacchetti, Allegra. "Novel transparent and flexible transistors for radiation harsh environment." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9204/.
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La scoperta dei semiconduttori amorfi ha segnato l’era della microelettronica su larga scala rendendo possibile il loro impiego nelle celle solari o nei display a matrice attiva. Infatti, mentre i semiconduttori a cristalli singoli non sono consoni a questo tipo di applicazioni e i s. policristallini presentano il problema dei bordi di grano, i film amorfi possono essere creati su larga scala (>1 m^2) a basse temperature (ad es. <400 °C) ottenendo performance soddisfacenti sia su substrati rigidi che flessibili. Di recente la ricerca sta compiendo un grande sforzo per estendere l’utilizzo di questa nuova elettronica flessibile e su larga scala ad ambienti soggetti a radiazioni ionizzanti, come lo sono i detector di radiazioni o l’elettronica usata in applicazioni spaziali (satelliti). A questa ricerca volge anche la mia tesi, che si confronta con la fabbricazione e la caratterizzazione di transistor a film sottili basati su ossidi semiconduttori ad alta mobilità e lo studio della loro resistenza ai raggi X. La micro-fabbricazione, ottimizzazione e caratterizzazione dei dispositivi è stata realizzata nei laboratori CENIMAT e CEMOP dell’Università Nova di Lisbona durante quattro mesi di permanenza. Tutti i dispositivi sono stati creati con un canale n di ossido di Indio-Gallio-Zinco (IGZO). Durante questo periodo è stato realizzato un dispositivo dalle ottime performance e con interessanti caratteristiche, una delle quali è la non variazione del comportamento capacitivo in funzione della frequenza e la formidabile resistenza alle radiazioni. Questo dispositivo presenta 114 nm di dielettrico, realizzato con sette strati alternati di SiO2/ Ta2O5. L’attività di ricerca svolta al Dipartimento di Fisica e Astronomia di Bologna riguarda prevalentemente lo studio degli effetti delle radiazioni ionizzanti su TFTs. Gli esperimenti hanno rivelato che i dispositivi godono di una buona stabilità anche se soggetti alle radiazioni. Infatti hanno mostrato performance pressoché inalterate anche dopo un’esposizione a 1 kGy di dose cumulativa di raggi X mantenendo circa costanti parametri fondamentali come la mobilità, il threshold voltage e la sub-threshold slope. Inoltre gli effetti dei raggi X sui dispositivi, così come parametri fondamentali quali la mobilità, si sono rivelati essere notevolmente influenzati dallo spessore del dielettrico.
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Taylor, Benjamin Owen. "Radiation monitoring in the MEO environment with GIOVE-A." Thesis, University of Surrey, 2008. http://epubs.surrey.ac.uk/771934/.
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The European GNSS system Galileo is being designed to operate 30 satellites in MEO. The design of these satellites requires a thorough understanding of the radiation environment. To this end a pair of radiation monitors, CEDEX and Merlin, were carried on the precursor mission GIOVE-A. These collected data on electrons, protons and heavy ions over the nominal mission life of 27 months. This work was aimed at understanding the response of the instruments and therefore understanding the radiation environment in MEO to determine if existing models of the environment are accurate enough for the design of the Ml Galileo constellation.
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Ehresmann, Bent [Verfasser]. "The Martian Radiation Environment - Early Mars and Future Measurements with the Radiation Assessment Detector / Bent Ehresmann." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/1021342602/34.
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Wahle, Peter Joseph 1961. "Radiation effects on power MOSFETs under simulated space radiation conditions." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277024.
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Application of power MOSFETs in spaceborne power converters was simulated by exposing devices to low-dose-rate ionizing radiation. Both radiation-hardened and nonhardened devices were tested with constant and switched gate biases during irradiation. In addition, some of the devices were under load. The threshold-voltage shifts were strongly bias dependent. The threshold-voltage shift of the nonhardened parts was approximately dose-rate independent, while the hardened parts exhibited significant dose-rate dependence. A pre-anneal dose-rate dependence was found for the interface-state buildup of the switched and positively biased devices, but the results for the switched devices were qualitatively different than those for the positively biased devices. The buildup of interface trapped charge was found to be the primary contributor to mobility degradation, which results in reduced drive capability and slower operation of the devices. These results indicate that new methods need to be utilized to accurately predict the performance of power MOSFETs in space environments.
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Köhler, Jan [Verfasser]. "Gamma, neutron separation in the Martian radiation environment / Jan Köhler." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/1020284099/34.
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Amutkan, Ozge. "Space Radiation Environment And Radiation Hardness Assurance Tests Of Electronic Components To Be Used In Space Missions." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612238/index.pdf.
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Space radiation is significantly harmful to electronic Components. The operating time, duration and orbit of the space mission are affected by the characteristic of the radiation environment. The aging and the performance of the electronic components are modified by radiation. The performance of the space systems such as electronic units, sensors, power and power subsystem units, batteries, payload equipments, communication units, remote sensing instruments, data handling units, externally located units,
and propulsion subsystem units is determined by the properly functioning of various electronic systems. Such systems are highly sensitive against space radiation.
The space radiation can cause damage to electronic components or functional failure on the electronics. A precisely methodology is needed to ensure that space radiation is not a threat on the functionality and performance of the electronics during their operational lives. This methodology is called as &rdquoRadiation Hardness Assurance&rdquo
. In this thesis, the hardening of electronics against space radiation is discussed. This thesis describes the space radiation environments, physical mechanisms, effects of space radiation, models of the space radiation environment, simulation of the Total Ionizing Dose, and &rdquo
Radiation Hardness Assurance&rdquo
which covers Total Ionizing Dose and Single Event Effects testing and analyzing of the electronics.
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Murdock, Christopher Paul. "A study of '2'1'0Pb in the atmosphere and estuarine sedimentary environment." Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310584.
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McClelland, Beverley. "Critical factors that influence staff retention in an acute perioperative environment a thesis in partial fulfilment of the degree in Master of Health Science at Auckland University of Technology, April 2004." Full thesis. Abstract, 2004. http://puka2.aut.ac.nz/ait/theses/McClellandB.pdf.
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Ersmark, Tore. "Geant4 Monte Carlo Simulations of the International Space Station Radiation Environment." Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4007.
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He, Jiaji. "Acoustic Waveguides and Sensors for High Temperature and Gamma Radiation Environment." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/101870.
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Sensing in harsh environments is always in great need. Although many sensors and sensing systems are reported, such as optical fiber sensors and acoustic sensors, they all have drawbacks.
In this dissertation, fused quartz and sapphire acoustic waveguides and sensors are developed for high temperature and heavy gamma radiation. The periodic structure, acoustic fiber Bragg grating (AFBG), is the core sensor structure in this dissertation. To better analyze the propagation of acoustic waves, the acoustic coupled more analysis is proposed. It could solve for the reflection spectrum of the AFBG with at most 2.1% error.
For the waveguide, the fused quartz "suspended core" waveguide is designed. It achieved strong acoustic energy confinement so surface perturbations no longer affected the wave propagation. Single crystal sapphire fiber features low acoustic loss, and survivability under high temperature. It is also chosen as an acoustic waveguide.
AFBGs are fabricated in both waveguides. The fused quartz suspended core AFBG is shown to sense temperature up to 1000 C and to have stable reading at 700 C for 14 days. The sapphire AFBG as a temperature sensor works up to 1500 C and also provides continuous stable reading at 1100 C for 12 days.
Both waveguides with AFBGs are then tested under long-term gamma radiation. Despite some fluctuations from radiation-related causes, the readings of both sensors generally remain stable.
Given the experimental observations, the fused quartz AFBG waveguide and the sapphire AFBG waveguide are shown to work well in high temperature and gamma radiations.Doctor of Philosophy
Sensing in harsh environments, like high temperature, high pressure, and corrosive environment, is always in great need. Efficient and safe operation of instruments like nuclear reactors could be better secured. Although many sensors and sensing systems are reported, such as optical fiber sensors and acoustic sensors, they all have drawbacks so new designs are constantly in need.newline In this dissertation, silica (a glass commonly acquired by melting sand) and sapphire (used in iphone screens due to its transparency and hardness) acoustic waveguides and sensors are developed. A periodic structure known as acoustic fiber Bragg grating (AFBG) is the core sensor structure in this dissertation. A calculation method is proposed first. Acoustic wave needs a waveguide to propagate somewhere further, and a new waveguide structure is made to keep the acoustic energy within the very center of the waveguide, so any change on the outer surface does not affect the wave inside. Also, sapphire has good acoustic property and is used. The AFBGs are fabricated in both waveguides. These sensing waveguides are shown to work at >1000 C temperature and provide stable reading for more than 10 days. Long term exposure to gamma radiation for weeks or months resulted in stable performances. Therefore, it is concluded that silica and sapphire waveguide sensors are successfully developed for high temperature and nuclear radiation applications.
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Weaver, Bess A. "Solar Ultraviolet Radiation Exposure in Outdoor Work Environment at Bowling Green, Ohio." University of Toledo Health Science Campus / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=mco1211995092.
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Craven, Paul A. "The biological effectiveness of heavy ion radiations in the environment." Thesis, Cranfield University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309835.
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Borrelli, Robert Angelo. "Characterization of Radioactivity in the Environment." Digital WPI, 1999. https://digitalcommons.wpi.edu/etd-theses/1085.
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"Ionizing radiation is produced as the result of the decay of an unstable nucleus. The standard measure of radioactivity is quantified according to the rate of disintegration of the unstable nucleus. This method of quantification does not incorporate the total amount of ionizing radiation that is associated with each disintegration of the radionuclide. The ionizing radiation that is produced as a result of decay is specific to a given radionuclide. A radionuclide can be conceptualized as a source of ionizing radiation. Disintegration of the unstable nucleus will therefore result in the continual release of ionizing radiation throughout the fixed existence of the radionuclide. This thesis will present a reasonable and practical adjustment to the current mechanism regarding the quantification of radionuclides. This adjustment will provide a basis to which the specific decay attributes of radionuclides can be normalized. Such a normalization will allow for direct comparisons among important inventories of radionuclides. This adjustment will be used to formulate a characterization of common radionuclides that exist in the environment. Such a characterization can provide a control inventory of ionizing radiation to which more specific systems of radionuclides can be compared."
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Matthiä, Daniel [Verfasser]. "The radiation environment in the lower atmosphere : a numerical approach / Daniel Matthiä." Kiel : Universitätsbibliothek Kiel, 2010. http://d-nb.info/1019902434/34.
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Underwood, Craig Ian. "Single event effects in commercial memory devices in the space radiation environment." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/743/.
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Campbell, Neil Scott. "A 'Monte Carlo' approach to thermal radiation distribution in the built environment." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243705.
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Mountain, Keith Richard. "A clear sky net radiation model for the high elevation glacial environment /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487681148542966.
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Zainuddin, Efendi. "A study of background radiation in the environment in Perth, Western Australia." Thesis, Zainuddin, Efendi (1992) A study of background radiation in the environment in Perth, Western Australia. PhD thesis, Murdoch University, 1992. https://researchrepository.murdoch.edu.au/id/eprint/51650/.
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The aim of this project is to develop and apply simple and inexpensive techniques for assessing the total environmental radiation dose for residents of the Perth Metropolitan Area. This dose is assumed to come from a variety of sources including indoor Rn(222) and Rn(220) daughters, radioactivity of building materials, soils and drinking water.
Techniques were developed to assess the contribution from each of these sources and a survey was carried out in the Perth Metropolitan Area to determine the annual effective dose equivalent from environmental radiation to members of the public.
To measure indoor Rn(222) and Rn(220) daughter working levels, a flexible version of the two count method was developed and adapted for use with a simple " Radon Sniffer " based on a low speed pump and alpha counter. Before applying this method to analyse field data, it was calibrated and tested using standard samples prepared in the laboratory. A computer program has been written to analyse integrated observed alpha counts after sampling, based on the mathematical analysis in this study.
The modified version of liquid scintillation technique developed by Prichard (1977) was used to determine the activity of radon, radium and other solid isotopes in groundwater collected from different parts of the Perth Metropolitan Area.
Results of indoor Rn(222) and Rn(220) daughter measurements and radioactivity in water indicate that there is a significant correlation between indoor Rn(222) and Rn(220) daughter concentration and radioactivity in groundwater with the geological structure and composition of soils and rocks.
The specific activity of building materials was measured by gamma spectrometry using a 2x2 cm Nal(TI) detector. From 8 different kinds of building materials measured, it appears that the radium and thorium contents are within the ranges found in other countries. Most of these materials have a radium equivalent within the standard limit. However red mud (bauxite processing residue) had a radium equivalent above the normal limit. This material is not commonly used as a building material in Perth.
Based on the results of measurements of six radiation sources, the average total estimated annual effective dose equivalent for residents from these sources in the Perth Metropolitan Area was 2.3 mSv. Background gamma radiation could add another 0.5 to 3 mSv per annum. This is much more than the public limit for artificial sources (1 mSv) recommended by the ICRP (1990). 76 % of the average total dose is contributed by indoor Rn(222) and Rn(220) daughters with Rn(222) daughters contributing 47.4 % (1.2 mSv) and Rn(220) daughters 28.4 % (0.6 mSv) of the average total dose. Radioactivity of local building materials contributed approximately 19 % (0.4 mSv), while radon, radium and solid isotopes in groundwater contributed only 3 % (0.07 mSv), 0.3 % (0.006 mSv) and 2 % (0.04 mSv) to the average total annual effective dose equivalent respectively. The average total annual effective dose equivalent from all sources in this study could be overestimated since the sampling procedure was not truly random. Many of the samples of indoor Rn(222) and Rn(220) daughters were obtained from an area which contains granite and laterite rocks.
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Medvedeva, Natalia Gennadievna. "Influence of cell environment on micronucleation in Chinese hamster ovary cells." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2790.
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The irradiation of cells in culture is an essential part of many radiation biology experiments. Since these experiments necessarily involve the irradiation of cell culture vessels and nutrient medium, the possibility of effects due to the interactions of irradiated material with growing cells needed to be investigated.
In the present study the micronucleus frequency in Chinese hamster ovary (CHO) cells as a function of such parameters as type of radiation, type of cell substrate, changes in cell environment, and time course of the effect were characterized. Observations of the persistence of micronucleus formation in irradiated CHO cells reveal that the number of cells containing micronuclei reaches its maximum within nine hours after irradiation and remain elevated for at least five days. The influence of the cell environment on micronucleus formation in CHO cells was examined by plating cells in preirradiated nutrient medium or on preirradiated cell culture vessels. In all experiments, pre-irradiation of the cell substrate (the culture dish or culture dish filled with medium) led to a significantly higher micronucleus frequency than when cells were plated on un-irradiated substrate. The difference is most pronounced at the lowest doses examined.
These results suggest that methods of cell culture vessel sterilization and the composition of cell attachment surfaces could be confounding factors, particularly in the experiments which are intended to examine the response of cells exposed to low doses of ionizing radiation.
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Acosta, Luis Roberto. "The attenuation of biologically active solar radiation (UV-B) in Mexico City environment." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq21677.pdf.
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Walden, Aleksi. "SMOS satellite hardware anomaly prediction methods based on Earth radiation environment data sets." Thesis, Luleå tekniska universitet, Rymdteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59789.
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SMOS (Soil Moisture and Ocean Salinity) is ESA's Earth Explorer series satellite carrying the novel MIRAS (Microwave Imaging Radiometer with Aperture Synthesis) interferometric synthetic aperture radar. Its objective is monitoring and studying the planet's water cycle by following the changes in soil moisture levels and ocean surface salt concentrations on a global scale. The success of the mission calls for nearly uninterrupted operation of the science payload. However, the instrument experiences sporadically problems with its hardware, which cause losses of scientific data and may require intervention from ground to resolve. The geographical areas in which most of these anomalies occur, polar regions and the South-Atlantic anomaly, give cause to assume these problems are caused by charged particles in the planet's ionosphere. In this thesis, methods of predicting occurrence of hardware anomalies from indicators of Earth radiation environment are investigated.
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Lizarrage, Adrian, Brittany Lynn, and Jeremiah Lange. "Remote Imaging System Acquisition (RISA) Space Environment Multispectral Imager." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/604306.
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ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, CaliforniaThe purpose of the NASA Remote Imaging System Acquisition space camera prototype is to integrate multiple optical instruments into a small wireless system using radiation tolerant components. This stage of prototyping was the development of a broadband variable-focus camera that can transmit data wirelessly. A liquid lens in conjunction with a cerium doped double gauss eliminates traditional focusing mechanisms.
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DALAQUA, JUNIOR LEONARDO. "Contribuicao para a aplicacao do detector Phoswich na analise de amostras ambientais." reponame:Repositório Institucional do IPEN, 1989. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9910.
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Made available in DSpace on 2014-10-09T12:32:43Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:09:03Z (GMT). No. of bitstreams: 1 03366.pdf: 1008030 bytes, checksum: 3c4f25e5172a0780c985f8c0dd3059a8 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Jonsson, Ida, and Maria Åsdell. "Följsamhet till användning av strålskydd." Thesis, Umeå universitet, Institutionen för omvårdnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-115770.
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Syftet. Att kartlägga följsamhet till användning av strålskydd bland perioperativ personal. Bakgrund. Sjuksköterskan ska arbeta förebyggande för att värna om sin egen, kollegor och patienters hälsa. På operationsavdelningen förekommer genomlysning vid operationsingrepp. Forskning har visat att röntgenstrålning är skadligt och riktlinjer finns som beskriver hur personal ska arbeta strålsäkert. Få studier har hittats som visar huruvida personalen följer riktlinjer. Metod. Studien är en tvärsnittsstudie och en enkät delades ut under oktober 2015 till perioperativ personal (n=69) vid två sjukhus i övre Norrland. Deltagarna arbetade som operationssjuksköterskor, anestesisjuksköterskor och undersköterskor samt deltog vid operationsingrepp där genomlysning förekom. Enkäten bestod av 16 frågor med både slutna och öppna svarsalternativ. Data analyserades med statistikprogrammet SPSS 23.0. Chi-två test och Fisher’s exakta test användes för att testa skillnader mellan professioner. Resultat. Majoriteten av deltagarna skattade att de ofta/alltid använde röntgenförkläde vid genomlysning. Ingen signifikant skillnad i användandet av röntgenförkläde eller halskrage fanns mellan professionerna. Däremot fanns en signifikant skillnad i hur professionerna rapporterade att de skyddade sig vid olika operationsingrepp. Flertalet av deltagarna ansåg sig ha goda kunskaper kring strålskydd men mer än hälften önskade ändå mer utbildning. Slutsats. Genom preventivt arbete så som återkommande utbildning om strålskydd och strålningens risker kan den perioperativa personalen minska risken att drabbas av ohälsa. Resultatet i föreliggande studie visar att området behöver utforskas mer och instrumentet kan användas vid en nationell undersökning.Aims. Investigate the compliance with the use of radiation protection among perioperative personnel. Background. In the operating theatre interventions occurs in surgical procedures. Research has shown that X-ray radiation is harmful and there are guidelines describing how personnel should work for radiation safety. Few studies where found that shows whether personnel complies with the guidelines. Methods. The study is a cross-sectional study and a questionnaire was distributed in October 2015 to the perioperative personnel (n=69) working at two hospitals in Northern Sweden. Participants worked as theatre nurses, nurse anesthetists and enrolled nurse, and participated in surgical procedures where fluoroscopy occurred. The questionnaire consisted of 16 questions with both closed and open response options. Data were analyzed using SPSS 23.0. Chi-square test and Fisher's exact test was used for testing differences between professions. Results. The majority of participants reported that they often/ always used the apron during fluoroscopy. No significant difference in the use of apron and thyroid shield was found between professions. Significant difference was found in how the professions reported that they protect themselves at different surgical procedures. The majority of the participants reported good knowledge about radiation protection but still more than half wanted more education. Conclusion. Preventive work as recurrent education about radiation protection and radiation risks may reduce the risk of illness among perioperative staff. Results from the present study shows that the area needs to be explored more and this instrument can be used for a national survey.
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Phillips, Stanley David. "Single event effects and radiation hardening methodologies in SiGe HBTs for extreme environment applications." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45854.
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Field-effect transistor technologies have been critical building blocks for
satellite systems since their introduction into the microelectronics industry. The
extremely high cost of launching payloads into orbit necessitates systems to have
small form factor, ultra low-power consumption, and reliable lifetime operation,
while satisfying the performance requirements of a given application. Silicon-based
complementary metal-oxide-semiconductors (Si CMOS) have traditionally been able to
adequately meet these demands when coupled with radiation hardening techniques that
have been developed over years of invested research. However, as customer demands
increase, pushing the limits of system throughput, noise, and speed, alternative
technologies must be employed. Silicon-germanium BiCMOS platforms have been
identfied as a technology candidate for meeting the performance criteria of these
pioneering satellite systems and deep space applications, contingent on their ability to
be hardened to radiation-induced damage. Given that SiGe technology is a relative new-
comer to terrestrial and extra-terrestrial applications in radiation-rich environments,
the same wealth of knowledge of time-tested radiation hardening methodologies has
not been established as it has for Si CMOS. Although SiGe BiCMOS technology has
been experimentally proven to be inherently tolerant to total-ionizing dose damage
mechanism, the single event susceptibility of this technology remains a primary concern.
The objective of this research is to characterize the physical mechanisms that drive the
origination of ion-induced transient terminal currents in SiGe HBTs that subsequently
lead to a wide range of possible single event phenomena. Building upon this learning,
a variety of device-level hardening methodologies are explored and tested for efficacy.
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Aguilar, Alexa Christine. "Characterization of commercial step-down converter performance in the low Earth orbit radiation environment." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122403.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 87-95).
We characterize three commercial step-down DC-DC converters for the Low Earth Orbit (LEO) space radiation environment. Commercial space industry is shifting spacecraft design philosophy toward accepting more risk for shorter lead times, lower costs, and high instrument performance. This shift opens up the Commercial Off The Shelf (COTS) electronics market to space applications. To quantify the risks associated with using COTS parts, components must be tested in flight-like configurations and conditions and their response to environmental stresses characterized. Few data exist in literature on the performance of DC-DC converters in the space radiation environment despite their ubiquity in designs and key role in operation for which the alternative is prohibitively expensive. This thesis introduces the space radiation environment and resulting effects. We then model the environment for two LEO constellation configurations and determine the maximum expected radiation levels over the mission lifetime. These levels are then used to inform radiation tests. The DC-DC converters are Total Ionizing Dose (TID) and Single Event Effects (SEE) tested in radiation conditions representative of the LEO space radiation environment. These devices demonstrate radiation tolerance in both tests, with a minimum TID tolerance of 60 krad(Si) and experience no destructive latch-up behavior to about 90 MeV-cm²-mg⁻¹. A first order reliability analysis shows these parts introduce little additive risk to spacecraft design.
by Alexa Christine Aguilar.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
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Mason, Sammuel P. "Atmospheric effects on radio frequency (RF) wave propagation in a humid, near-surface environment." Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/theses/2010/Mar/10Mar%5FMason.pdf.
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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2010.Thesis Advisor(s): Guest, Peter S. ; Goroch, Andreas K. "March 2010." Author(s) subject terms: Electromagnetic propagation, electromagnetic scattering, groundwave propagation, mathematical techniques, variance reduction. Includes bibliographical references (p. 67-68). Also available in print.
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Avelin, Maria, and Linn Heimersson. "Operationssjuksköterskans omvårdnadsansvar i samband med röntgen vid operation." Thesis, Karlstads universitet, Institutionen för hälsovetenskaper (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-75917.
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Introduktion: I samband med röntgen vid operation föreligger en risk att patienten drabbas av vårdskada. Det ställer krav på att operationssjuksköterskan är välinformerad och har den kompetens som behövs för att optimera röntgenanvändning vid operation. Syfte: Att belysa operationssjuksköterskans omvårdnadsansvar av patienten i samband med röntgenanvändning vid operation. Metod: En litteraturstudie där vetenskapliga forskningsartiklar utgjorde informationskällan. Informationen har sedan analyserats, och kategorier och underkategorier har skapats. Resultat: Baseras på tio vetenskapliga artiklar och presenteras i form av två kategorier och sju underkategorier som arbetades fram under analysprocessen. Den första kategorin; ”Skapa välmående för patienten” byggs upp av underkategorierna ”Medvetenhet om patientens utsatthet”, ”Lugn och trygg vårdmiljö” och ”Information till patienten”. Den andra kategorin; ”Minska risken för vårdskada” innehåller underkategorierna ”Skydda patienten”, ”Möjlighet att förbereda arbetet”, ”Skapa en helhetsbild av patienten” och ”Minska stråldosen”. Konklusion: Operationssjuksköterskan har möjlighet att påverka vården av patienten när röntgen används vid operation, men för att kunna ha möjlighet att påverka vården och nå goda resultat behöver operationssjuksköterskorna ha kunskap om det omvårdnadsansvar som åligger dem.Introduction: When using X-ray in the operating room the patient is at risk of health care injury. It is required for the operating theatre nurse to be well informed and has the necessary skills to optimize X-ray use. Purpose: To highlight operating theatre nurses responsibility when using x-ray in surgery. Method: A literature study where scientific research articles was the source of information. The information has then been analyzed and categories and subcategories have been created. Result: Based on ten studies and presented in the form of two main categories and seven subcategories. The first main category ”Creating wellbeing for the patient” consists of the subcategories ”Awareness of the patients vulnerability”, ”Calm and secure environment” and ”Patient information”. The other main category ”Reduce risk of healthcare injury” consists of the subcategories ”Protect the patient”, ”Prepare the work”, ”Patients overall picture” and ”Reduce radiation”. Conclusion: The operating theatre nurse has the ability to influence the care when X-ray is used in surgery, but knowledge and insight about the responsibility is essential.
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Alexander, Andrew William. "MMCTP : a radiotherapy research environment for Monte Carlo and patient-specific treatment planning." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101699.
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Accurate dose calculations and analysis tools are essential to radiotherapy treatment planning. Radiotherapy deliveries utilize the information provided by the treatment planning system and it is generally accepted that clinical outcome can be improved if accuracy in the dose delivery is further improved. Proven Monte Carlo calculations increase the planning accuracy however, most radiotherapy departments do not use Monte Carlo. The McGill Monte Carlo treatment planning system, MMCTP, provides a flexible software environment to integrate Monte Carlo planning with current and new treatment modalities and deliveries. The MMCTP design consists of a graphical user interface, which runs on a simple workstation connected through standard secure-shell protocol to a cluster for lengthy Monte Carlo calculations. The impact of this tool lies in the fact that it allows for systematic, platform independent, large-scale Monte Carlo planning calculations for different treatment sites. Various measurements and patient recalculations were preformed to validate the software and ensure proper functionality.
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Krithivasan, Ramkumar. "Design of High-Speed SiGe HBT BiCMOS Circuits for Extreme Environment Applications." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14505.
Full textAbstract:
The objective of this work is to investigate the suitability of applying silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) bipolar complementary metal oxide semiconductor (BiCMOS) technology to extreme environments and to design high-speed circuits in this technology to demonstrate their reliable operation under these conditions. This research focuses on exploring techniques for hardening SiGe HBT digital logic for single event upset (SEU) based on principles of radiation hardening by design (RHBD) as well as on the cryogenic characterization of SiGe HBTs and designing broadband amplifiers for operation at cryogenic temperatures. Representative circuits ranging from shift registers featuring multiple architectures to broadband analog circuits have been implemented in various generations of this technology to enable this effort.
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Jessee, Emory Jerry. "Radiation ecologies: bombs, bodies, and environment during the atmospheric nuclear weapons testing period, 1942-1965." Diss., Montana State University, 2013. http://etd.lib.montana.edu/etd/2013/jessee/JesseeE0513.pdf.
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From 1945 to 1963 the United States Atomic Energy Commission detonated over 200 nuclear weapons tests at its Nevada and Pacific test sites, irradiating every living thing on the planet. Much of the historical scholarship on the period has focused on the scientific debate over the health effects of low-level radiation exposure or on determining what and when the Atomic Energy Commission knew about the health effects fallout. This dissertation, however, argues that the growth of ecological thinking about the health effects of fallout exposure in environmental sciences such as ecology, oceanography, and meteorology dramatically reshaped what was known about radiological risk and provided the scientific foundation for the Limited Test Ban Treaty. By highlighting the ways that radiation traveled beyond the boundaries of the test sites and became incorporated into critical human food chains, this ecological way of perceiving fallout largely replaced previous approaches to fallout risks derived from the discipline of health physics that focused on external forms of radiation exposure and ideas of spatial containment. This dissertation, however, also argues that fallout radiation proved much more than a menacing pollutant. Because environmental scientists can utilize radiation as a tool to trace out structure and function of the ecosystem, as well as oceanic and atmospheric motions, it also emerged during this period as a critical scientific practice. In tracing radiation as it moved through the environment, environmental scientists not only made legible the connections between the health of human bodies and the irradiated environment, but also demonstrated empirically that the earth was a spatially integrated biosphere. Such realizations, this dissertation concludes, formed an important footing the nascent environmental movement and helped establish the authority of the environmental sciences in matters of environmental pollution and regulation.
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Andersson, Anton, and Birger Vaksdal. "Simulation of the Heavy Ion Contribution to the Radiation Environment onboard the International Space Station." Thesis, KTH, Fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-129324.
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The health risks from exposure to the space radiation environment makes it important to have reliable simulation models for the radiation doses inside spacecrafts. Simulations of the heavy ion parts, especially iron, of the Galactic Cosmic Ray (GCR) radiation has been carried out using the simulation software Geant4 with geometry models from the DESIRE project. The total dose rate from iron ions is found to be 1.57 Gy=d and dose equivalent is found to be 17 Sv=d. This means that iron contributes between 5% and 10% to the total dose equivalent from the GCR radiation, substantially higher than its relative abundance of 0.03 percent. 67% of the dose rate from iron comes from particles with energies in the range 1 000 - 10 000 MeV/nucleon, and 26% comes from particles in the 10 000 - 50 000 MeV/nucleon range. The great majority of the dose is deposited by iron ions, opposed to secondary particles. This result was not expected. Calculated dose rates are found not to be significantly dependent of the ISS altitude.
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Oliver, Hannah Elizabeth. "The impacts of optical radiation in the environment on skin : hazards, measurement, regulation and protection." Thesis, Brunel University, 2006. http://bura.brunel.ac.uk/handle/2438/5329.
Full textAbstract:
From 2001 to 2005, work was conducted at the Photobiology Unit at Ninewells Hospital in Dundee to examine the optical radiation environment and its implications for normal and diseased skin. Artificial sources of radiation were considered within the contexts of the hazards posed, measurement of the hazards, regulation concerning exposure and sources, and protection of abnormal skin from adversee ffects. The hazards posed by both ultraviolet (UV) and visible polychromatic sources were examined for normal and abnormal (chronic actinic dermatitis and solar urticaria) skin in an effort to predict the responses to such radiation. With current methodologiesi t was shown that responsesto polychromatic light cannot be forecast for normal and abnormal skin. Those hazards posed by light sources in the commercial sector are also considered. The sunbeds available in Perthshire and Dundee were evaluated spectroradiometrically and appropriate weighting functions applied. A case of adverse effects due to inappropriate use of an UV source is also presented and the implications are discussed. Two diode array spectroradiometers were evaluated for their potential as instruments to measure UV sources. It was shown that one instrument could be used to give measurementsw ith acceptablee rrors. However, later work with a different instrument of the same series showed that there are manufacturing issues to be resolved before these instruments are marketed for widespread use in dosimetry. Regulations governing exposure to and use of sources are considered where appropriate. Licensing of commercial sunbed parlours is suggested in order to enforce Health and Safety guidelines and the British Standard for such appliances, create a baseline for minimum standards of care within the commercial sector and safeguard public health. Lastly, it has been shown that skin sensitive to visible light can be protected with commercial makeup preparations.
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Fortkamp, Jonathan C. "Characterization of the radiation environment for a large area interim spent nuclear fuel storage facility /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488188894437725.
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Turnbull, David J. "Development of an improved shade environment for the reduction of personal UV exposure." University of Southern Queensland, Faculty of Sciences, 2005. http://eprints.usq.edu.au/archive/00001519/.
Full textAbstract:
The research from this project has quantified the solar UV environment beneath and surrounding typical local council public shade structures. The effects of changing seasons, atmospheric conditions, structural modifications and surrounding plant life on diffuse UV have been quantified. Strategies to improve current shade structures, so as to significantly reduce the levels of diffuse UV reaching the human body in the shade, have also been developed. For the shade structures used in this research it was found that ultraviolet protection factors ranged from 1.5 to 18.3 for a decreasing solar zenith angle. Correlations have been found relating diffuse erythemal UV to UV in the shade for clear skies and a changing solar zenith angle. The effect of changing atmospheric ozone levels on diffuse erythemal UV levels has been quantified. UV exposures were assessed for a decrease in scattered UV beneath specific shade structures by the use of two types of protection, namely, side-on polycarbonate sheeting and evergreen vegetation. Broadband radiometric and dosimetric measurements conducted in the shade of a scale model shade structure, during summer and winter, showed significant decreases in exposure of up to 65% for summer and 57% for winter when comparing the use and non-use of polycarbonate sheeting. Measurements conducted in the shade of four shade structures, with various amounts of vegetation blocking different sides, showed that adequate amounts and positioning of vegetation decreased the scattered UV in the shade by up to 89% when compared to the shade structure that had no surrounding vegetation. This research shows that major UV reduction could be achieved by the ‘shade creation and design industry’, and that shade guidelines should be updated as soon as possible.
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Najafizadeh, Laleh. "Design of analog circuits for extreme environment applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31796.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: Cressler, John; Committee Member: Papapolymerou, John; Committee Member: Shen, Shyh-Chiang; Committee Member: Steffes, Paul; Committee Member: Zhou, Hao Min. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Larsson, Oscar. "Analysis of the Radiation Environment on Board the International Space Station Using Data from the SilEye-3/Alteino Experiment." Doctoral thesis, KTH, Partikel- och astropartikelfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145339.
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This thesis presents an analysis of the radiation environment on board the Russian section of the International Space Station (ISS) using data from the SilEye-3/Alteino experiment. As part of the analysis the efficiency and response of the SilEye-3/Alteino detector was studied. The relative nuclear abundance is generally in agreement with expected results. The presence of odd Z nuclei is significantly increased when compared with measurements outside the ISS. However, in ISS-y (Starboard-Ports) and z (Nadir-Zenith) directions an underabundance of carbon and oxygen nuclei is seen, whereasin x (Forward-Aft) there seemes to be an overabundance. One possible explanation is the absence of high-Z material in the ISS module wall for y and z . Whereas in x, most of the main body of the ISS is in front of the detector and the amount of high-Z material (i.e. aluminium) is large. The nalysis of fragmentation of iron into a range of secondary nuclei (15≤Z ≤25) indicates an aluminium hull equivalent thickness of 8-9 cm in y- and z-directions. For x the aluminium hull equivalence amounts to about 17 cm. Flux, LET, dose and dose equivalent rates present a clear anisotropy in the different orthogonal directions of the ISS, with rates consistently lower in x. This effect is more pronounced for the heavy-ion component (LET >50 keV/μm). Measureddose rates vary from 25 μGy/day to 75 μGy/day, depending on location, orientationand configuration of the detector. The dose equivalent varies from 50 μSv/day toalmost 470 μSv/day.The shielding effect of the polyethylene amounts to 25-37% dependent on loca-tion and orientation inside the ISS. The majority of the reduction occurs duringpassages through the SAA. A Geant4 comparison with the Phits simulations code have been preformed as an initial survey into the treatment of hadronic physics for heavy ions in Geant4.QC 20140521
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Lourenco, Nelson Estacio. "An assessment of silicon-germanium BiCMOS technologies for extreme environment applications." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45959.
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This thesis evaluates the suitability of silicon-germanium technology for electronic systems intended for extreme environments, such as ambient temperatures outside of military specification (-55 degC to 125 degC) range and intense exposures to ionizing radiation. Silicon-germanium devices and circuits were characterized at cryogenic and high-temperatures (up to 300 degC) and exposed to ionizing radiation, providing empirical evidence that silicon-germanium is an excellent platform for terrestrial and space-based electronic applications.
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Dartnell, Lewis R. "Computer modeling and experimental work on the astrobiological implications of the martian subsurface ionising radiation environment." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/14772/.
Full textAbstract:
Any microbial life extant in the top meters of the martian subsurface is likely to be held dormant for long periods of time by the current permafrost conditions. In this potential habitable zone, a major environmental hazard is the ionising radiation field generated by the flux of exogenous energetic particles: solar energetic protons and galactic cosmic rays. The research reported here constitutes the first multidisciplinary approach to assessing the astrobiological impact of this radiation on Mars. A sophisticated computer model has been constructed de novo to characterise this complex subsurface ionising radiation field and explore the influence of variation in crucial parameters such as atmospheric density, surface composition, and primary radiation spectra. Microbiological work has been conducted to isolate novel cold-tolerant bacterial strains from the Dry Valleys environment of Antarctica, an analogue site to the martian surface, and determine their phylogenetic diversity and survival under high-dose gamma-ray exposure frozen at -79!C, a temperature characteristic of the martian mid-latitude permafrost. Original results are presented pertinent to microbial survival time, persistence of organic biomarkers, and calibration of the optically stimulated luminescence dating technique, as a function of depth. The model predicts a population of radiation resistant cells to survive in martian permafrost soil for 450,000 years at 2 m depth, the proposed drill length of the ExoMars rover. The Antarctic culturing studies identified representatives of four bacterial genera. The novel isolate Brevundimonas sp. MV.7 is found to show 99% 16S sequence similarity to cells discovered in NASA spacecraft assembly clean rooms, with the experimental irradiation determining this strain to suffer 10-6 population inactivation after a radiation dose of 7.5 kGy in martian permafrost conditions. Integrating the modelling and experimental irradiation, this research finds a contaminant population of such cells deposited just beneath the martian surface would survive the ambient cosmic radiation field for 117,000 years.
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Luscombe, Christopher James. "Exposure to ultraviolet radiation and susceptibilty to sporadic prostate cancer : a study of gene-environment interactions." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288652.
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Lohmeyer, Whitney Quinne. "Space radiation environment impacts on high power amplifiers and solar cells on-board geostationary communications satellites." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98682.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 273-292).
Communications satellite operators maintain archives of component telemetry to monitor system function. Operators generally do not typically use the telemetry data for scientific analysis of the space radiation environment effects on component anomalies or performance. We partnered with four geostationary (GEO) operators, acquired >1 million hours of telemetry, and combined these data with space weather observations to investigate relationships between space weather and hardware performance. We focused on the effects of space weather on two component types: solar cells and high power amplifiers. For solar cells, by augmenting >20 years of GEO telemetry with separate GEO space weather measurements, we calculated both on-orbit degradation of Si and GaAs solar cells in an annual average sense, and also quantified the degradation of cells during severe solar proton events (SPEs) of 10 MeV protons > 10,000 pfu. A functional relationship between the amount of degradation and proton fluence is also considered. We used the calculated degradation to evaluate several combinations of space weather environment models with solar cell degradation models and found that predicted performance is within 1% of the observed degradation. These models had not previously been validated using multiple on-orbit GEO datasets. We did not find a model pairing that consistently outperformed the others over all of the datasets. For high power amplifiers, through the use of statistical analysis, simulations, and electron beam experiments we conducted a root-cause analysis of solid state power amplifier (SSPA) anomalies on-board eight GEO satellites. From the statistical analysis, we identified that the occurrence of anomalies was not random with respect to the space weather environment, but that there appeared to be a relationship to high-energy electron fluence for periods of time between 10 - 21 days before the anomalies. From the simulations and electron beam lab tests, we demonstrated that internal charging occurs in the amplifier chain, potentially identifying a cause for the observed anomalies. We substantiated an approach toward understanding space weather effects on space components by obtaining and using long-duration archives of standard commercial telemetry for scientific analysis. The analysis of large telemetry data sets of similar components over long periods of time improves our ability to assess the role of different types of space weather events in causing anomalies and helps to validate models. The findings in this work that relate deep dielectric charging to component anomalies and solar proton events to solar cell degradation make use of only a small fraction of the potentially available commercial geostationary satellite telemetry. Expansion of this work would provide additional insights on the role of space weather to the science community and to the satellite design and operator community.
by Whitney Quinne Lohmeyer.
Ph. D.
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Begg, Fiona H. "Anthropogenic '1'4C in the natural (aquatic) environment." Thesis, University of Glasgow, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300458.
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Secondo, Raffaello. "Upgrades of the RadMON V6 and its Integration on a Nanosatellite for theAnalysis and the Comparative Study of the CHARM and Low Earth Orbit Environments." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS063/document.
Full textAbstract:
Les champs radiatifs dans le complexe d’accélérateurs du CERN sont caractérisés par des particules mixtes avec un large spectre d’énergie. Le système de surveillance des radiations, le RadMon, a été développé pour la mesure distribuée, et en temps réel, des radiations et ses effets sur l’électronique installée dans les tunnels et les zones expérimentales. Pendant la première phase d’opération du RADMON, un problème critique a été identifié sur les mémoires SRAM utilisées comme capteurs de fluence des hadrons de hautes énergies. Un large nombre de MCU (Multiple Cell Upsets), générés par des microlatchups, ont commencé à apparaître sur les RADMONs, affectant ainsi la précision de mesure de la fluence. Une étude de la cause de cet effet a été réalisée et une solution utilisant un algorithme de détection et de correction en ligne, embarqué sur un FPGA, a été évaluée et mise en place sur les RADMONs installés dans les zones du SPS, PSB, NA62, HiRadMat, ALICE et CHARM.Par ailleurs, dans le cadre du projet CELESTA, une étude de faisabilité a été réalisée pour valider l’adaptation du RadMon à une charge utile pour des applications CubeSat de dimension 1U. Le travail de recherche a été soutenu par le service de transfert de connaissance du CERN en collaboration avec l’Université de Montpellier, le Centre Spatial Universitaire.Les tests expérimentaux ont été effectués dans le nouveau moyen de test CHARM. CHARM offre la possibilité de reproduire les champs radiatifs mixtes présents dans les installations du CERN ainsi que les basses orbites terrestres (LEO).Un module autonome de charge utile pour Cubesat a été développé et équipé avec des capteurs permettant de mesurer dose ionisante ainsi que la fluence des hadrons de haute énergie. Par ailleurs une expérience permettant de détecter des latchups a été ajoutée au module. Les résultats des tests ont permis la définition d’une nouvelle procédure pour la qualification des nano satellites au niveau des radiations sur le système. Ce travail de thèse détaille l’approche suivie pour le choix et la caractérisation des composants utilisés sur la charge utile.La charge utile de CELESTA est le premier projet du CERN sur le sujet de la science des "small satellites". Il représente la première étape d’un intérêt croissant de l’utilisation du moyen de test CHARM pour des missions en environnement spatialRadiation fields in the CERN accelerator complex are characterized by mixed particles with broad energy ranges. A Radiation Monitoring System, called "RadMon", was developed for the distributed, on-line measurement of the complex radiation fields and their effect on the electronics installed in areas with a harsh radiation environment. The most recent version of the RadMon revealed a critical issue soon after deployment in the tunnel and the experimental areas. Multiple Cell Upsets (MCUs) arising from microlatchup events started showing up on the SRAM-based particle flux sensors equipped by the system, ultimately affecting the measurement and resulting in corrupted data and accuracy losses. A study of the generation of this effect was performed, and a solution using an on-line detection and correction algorithm embedded on an FPGA, was evaluated and implemented on the RadMon device.Furthermore, in the framework of the project CELESTA, a feasibility study was carried out to validate the adaptation of the RadMon to a 1U CubeSat payload. The research was supported by the CERN Knowledge Transfer as a collaboration between the University of Montpellier, the Centre Spatial Universitaire and CERN. Experimental tests were performed at the new CHARM facility, which allows the characterization of small components, as well as large systems, in a mixed-field representative of the Low Earth Orbit.A stand-alone payload module for 1U CubeSats was developed and equipped withsensors of ionizing dose and high energy hadron fluence. In addition a Latchup Experiment was added on the module as part of the scientific goals of the mission. Results of experimental tests led to the definition of a new procedure for the radiation qualification of small satellites at system level. Details of the characterization and the choice of components are presented together with the approach followed.The payload is the first small satellite module ever designed at CERN. It representsthe first step of an increasing interest towards radiation qualification at CHARM of electronics for low orbit space missions
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Thrivikraman, Tushar K. "SiGe BiCMOS phased-array antenna front-ends for extreme environment applications." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37141.
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The objective of this research is to understand the design and performance of state-of-the-art silicon-germanium (SiGe) BiCMOS high-frequency circuits for phased- array radar and wireless communication systems operating in extreme environment conditions. This work investigates the performance of RF circuits over a wide- temperature and exposure to a radiation intensive environment. The design and characterization of a fully integrated transmit/receive (T/R) module and integra- tion onto a multi-element antenna array is presented. In addition, individual circuit blocks are characterized in these extreme environments.
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Wilcox, Edward. "Silicon-germanium devices and circuits for cryogenic and high-radiation space environments." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33850.
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This work represents several years' research into the field of radiation hardening by design. The unique characteristics of a SiGe HBT, described in Chapter 1, make it ideally suitable for use in extreme environment applications.
Chapter 2 describes the total ionizing dose effects experienced by a SiGe HBT, particularly those experienced on an Earth-orbital or lunar-surface mission. In addition, the effects of total dose are evaluated on passive devices.
As opposed to the TID-hardness of SiGe transistors, a clear vulnerability to single-event effects does exist. This field is divided into three chapters. First, the very nature of single-event transients present in SiGe HBTs is explored in Chapter 3 using a heavy-ion microbeam with both bulk and SOI platforms [31]. Then, in Chapter 4, a new device-level SEU-hardening technique is presented along with circuit-design techniques necessarily for its implementation. In Chapter 5, the circuit-level radiation-hardening techniques necessarily to mitigate the effects shown in Chapter 3 are developed and tested [32].
Finally, in Chapter 6, the performance of the SiGe HBT in a cryogenic testing environment is characterized to understand how the widely-varying temperatures of outer space may affect device performance.
Ultimately, the built-in performance, TID-tolerance, and now-developing SEU-hardness of the SiGe HBT make a compelling case for extreme environment electronics. The low-cost, high-yield, and maturity of Si manufacturing combine with modern bandgap engineering and modern CMOS to produce a high-quality, high-performance BiCMOS platform suitable for space-borne systems.