Relevant bibliographies by topics / Dose coefficients

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Academic literature on the topic 'Dose coefficients'

Author: Grafiati
Published: 24 March 2023

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Journal articles on the topic "Dose coefficients"

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Killough, George G., and Paul S. Rohwer. "14C DOSE COEFFICIENTS." Health Physics 90, no. 3 (2006): 273–75. http://dx.doi.org/10.1097/00004032-200603000-00011.

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Schultz, F. W., and J. Zoetelief. "Dose conversion coefficients for interventional procedures." Radiation Protection Dosimetry 117, no. 1-3 (2005): 225–30. http://dx.doi.org/10.1093/rpd/nci753.

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Veinot, K. G., N. E. Hertel, M. M. Hiller, and K. F. Eckerman. "Neutron dose coefficients for local skin." Journal of Radiological Protection 40, no. 2 (2020): 554–82. http://dx.doi.org/10.1088/1361-6498/ab805e.

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Vargo, George J. "The ICRP Database of Dose Coefficients." Health Physics 78, no. 3 (2000): 343. http://dx.doi.org/10.1097/00004032-200003000-00015.

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Dubeau, J., and J. Sun. "ELECTRON EYE-LENS OPERATIONAL DOSE COEFFICIENTS." Radiation Protection Dosimetry 188, no. 3 (2020): 372–77. http://dx.doi.org/10.1093/rpd/ncz295.

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Abstract In 2012, the International Commission on Radiological Protection issued a recommendation for a reduced annual eye-lens dose limit in the face of mounting evidence of the risk of cataract induction. This led to worldwide research efforts in various areas including the dose simulation in realistic eye-models, the production of dosimeters and the elaboration of protection and operation fluence to eye-lens dose coefficients. In this last case, much efforts have been expanded with regards to photon operational coefficients for Hp (3) but much less for electron radiation. In this work, Hp (3) coefficients for electrons are presented following simulations using MCNP and compared to those that are available in the literature. It is found that, at energies of 1 MeV and less, Hp (3) coefficients depend strongly on the selected electron transport options and on the dose tally volume. The effect of these differences is demonstrated for two beta emitters.
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Kanti, Hassan Al, Otman El Hajjaji, Tarek El Bardouni, and Maged Mohammed. "Neutron conversion coefficients of ambient dose equivalent and personal dose equivalent." Polish Journal of Medical Physics and Engineering 28, no. 1 (2022): 52–59. http://dx.doi.org/10.2478/pjmpe-2022-0006.

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Abstract Introduction: This work aims to calculate the ambient and personal dose equivalent conversion coefficients. Material and methods: The conversion coefficients have been calculated using MC simulation. Additionally, this paper proposes a new method that depends on an analytical approach. Results: The obtained results in good agreement between MC and an analytical approach were observed. The obtained results were compared to those published in ICRU 57 report. Conclusions: We deduced that the analytical approach is as effective and suitable as the MC simulation to calculate the operational quantity conversion coefficients.
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Opreanu, Razvan C., Ranji Samaraweera, and John P. Kepros. "Effective Dose to Dose-Length Product Coefficients for Calculation of CT Effective Dose." Radiology 252, no. 1 (2009): 315–16. http://dx.doi.org/10.1148/radiol.2521090245.

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Mares, V., and G. Leuthold. "Altitude-dependent dose conversion coefficients in EPCARD." Radiation Protection Dosimetry 126, no. 1-4 (2007): 581–84. http://dx.doi.org/10.1093/rpd/ncm118.

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Khursheed, A. "Uncertainties in Dose Coefficients for Systemic Plutonium." Radiation Protection Dosimetry 78, no. 2 (1998): 121–26. http://dx.doi.org/10.1093/oxfordjournals.rpd.a032342.

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Phipps, A. W., T. J. Silk, and T. P. Fell. "The ICRP CD-ROM of Dose Coefficients." Radiation Protection Dosimetry 79, no. 1 (1998): 363–65. http://dx.doi.org/10.1093/oxfordjournals.rpd.a032427.

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Dissertations / Theses on the topic "Dose coefficients"

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Finklea, Lauren. "Room radiation dose coefficients for external exposure." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53943.

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In instances where a building room is radiologically contaminated, dose rate coefficients are needed to estimate the dose rate to the occupants. One’s position in the room, whether in the center of the room or the corner, could have an effect on dose rate. The Environmental Protection Agency (EPA) published in Federal Guidance Report 12 (EPA 1993) dose rate coefficients for idealized exposure geometries, including exposure to radionuclides distributed infinitely in various thicknesses of soil. The dimensions of the exposure plane were taken to be infinite in extent. Due to this assumption, using the Federal Guidance Report coefficients could lead to an incorrect estimate of dose rate inside a contaminated room. In order to apply the published coefficients for a structure, we developed Room Ratios using MCNP5 to compare air kerma rate of various room sizes and multiple building materials to the published infinite air kerma rate taking into account several receptor positions. Room Ratio values will be used for preliminary remediation risk assessment for environmental radionuclide clean up and be integrated into existing online tools and databases (epa-bprg.ornl.gov). The incorporation of ratios into these tools will update dose coefficients that previously accounted only for surface contamination (Eckerman 2010). Additionally, Room Ratios will allow Federal Guidance Report 12 dose coefficients application to customizable building materials and thickness.
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Larsson, Ylva. "Establishing low-energy x-ray fields and determining operational dose equivalent conversion coefficients." Thesis, Stockholm University, Medical Radiation Physics (together with KI), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8319.

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<p>Reference radiation fields for x-ray qualities are described by the International Organization of Standards (ISO). This study describes the procedure to establish nine different low energy X-ray qualities at the national metrology laboratory, Swedish Radiation Protection Authority, following the document ISO 4037. Measurements of tube voltage, half-value layer, mean energy and spectral resolution have been performed for qualities N-15, N-20, N-25, N-30, N-40, L-20, L-30, L-35 and L-55. Furthermore, dose equivalent conversion coefficients for operational quantities ambient dose equivalent, personal dose equivalent and directional dose equivalent have been calculated by folding the mono-energetic conversion factors with measured spectral distributions of the x-ray qualities. The spectral distributions were unfolded from pulse-height distributions to photon distributions using simulated data of the semi-conductor detector used for measurements, generated with the Monte Carlo code PENELOPE.</p>
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Nielsen, Adam Derek. "Monte Carlo calculation of fluence-to-ambient dose equivalent conversion coefficients for high-energy neutrons." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/16424.

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Santos, Josilene Cerqueira. "Determinação experimental da distribuição de dose absorvida em diferentes qualidades de feixes mamográficos." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-26042018-121103/.

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A dose glandular média é a grandeza utilizada para dosimetria em mamografia. Esta grandeza apresenta grande dependência com propriedades específicas referentes ao tipo de mama a ser avaliada, tais como sua glandularidade e espessura comprimida. Depende também das propriedades do espectro de raios X, tais como a combinação anodo/filtro e a tensão aplicada ao tubo, que modificam a camada semirredutora do feixe. A caracterização do feixe de raios X através da medição direta do seu espectro é um procedimento de alta complexidade e de difícil execução em sistemas de mamografia, devido à arquitetura dos equipamentos e da alta taxa de fluência de fótons característica dos feixes. Estes espectros representam a fonte de informações quantitativas e qualitativas mais completa do feixe. O objetivo geral desse trabalho é estimar distribuições de dose glandular em diferentes profundidades de materiais simuladores de tecido mamário por meio de espectros de raios X medidos em mamógrafos. Para isso, foram utilizadas técnicas radiográficas comumente empregadas na mamografia para o rastreamento do câncer de mama. Foi avaliado o comportamento da dose glandular média normalizada pelo kerma no ar incidente (DgNp) com parâmetros relacionados à mama (glandularidade e espessura) e aos espectros (camada semirredutora, tensão, combinação alvo/filtro). Primeiramente, foi desenvolvida uma metodologia experimental para medição dos espectros de raios X nos mamógrafos. Em seguida, foram propostos os seguintes métodos de cálculo da DgNp utilizando esses espectros: Método I, que calcula a DgNp com espectros incidentes; Método II, que utiliza espectros incidentes e transmitidos para este cálculo e Método III, que usa espectros incidentes e transmitidos para estimar a distribuição de dose em profundidade. Por fim, para efeito de comparação, a distribuição da DgNp também foi estimada utilizando dosímetros termoluminescentes (TLDs). A metodologia desenvolvida para medição de espectros mostrou-se eficaz para posicionamento e alinhamento adequados do detector no feixe e consequentemente a medição dos espectros diretos. Os espectros incidentes experimentais mostraram boa concordância com espectros simulados. Os resultados mostraram uma distribuição bem-comportada desses coeficientes (DgNp), com tendência linear ou exponencial, com relação aos parâmetros analisados. Para um dado espectro, os valores de DgNp apresentaram decrescimento exponencial com a espessura do material simulador ao tecido mamário e dependencia linear com a glandularidade. Além disso, esses coeficientes crescem linearmente com o aumento da camada semirredutora e, consequentemente, com a energia efetiva. A partir das distribuições de DgNp (obtidas pelo Método III) foi possível estimar a dose no volume completo da mama com diferença máxima de 5,2% dos valores obtidos com o Método II. A variação da DgNp com a profundidade obtidas com TLDs mostrou-se bastante coerente com os resultados observados com a utilização do Método III. Conclui-se que é possível avaliar a dose glandular em mamografia utilizando espectros de raios X e que a metodologia proposta tem potencial para ser aplicada como procedimentos alternativos para dosimetria em mamografia.<br>The mean glandular dose is the quantity used for dosimetry in mammography. This quantity has a strong dependence with some properties of the evaluated breast, such as its glandularity and compressed thickness. It also depends on the X-ray spectrum used for the mammographic image production, such as the target/filter combination and the tube voltage, which are related to the half value layer (HVL) of the beam. The X-ray beam characterization by means of the direct measurement of its spectrum is a complex procedure, and it is difficult to be implemented in clinical systems due to the architecture of the mammography equipment and the high photon fluence rates. These spectra provide a complete qualitative and quantitative information of the X-ray beam. The general objective of this work is to estimate mean glandular dose distributions in different depths of breast tissue-equivalent materials (bTEM) considering the X-ray spectra measured in clinical mammography devices. Radiographic techniques commonly applied for breast cancer screening were used. The behavior of the mean glandular dose normalized to the incident air kerma (DgNp), with parameters related to the breast (glandularity and compressed thickness) and to the mammographic spectra (HVL, tube voltage, target/filter combination), was evaluated. First, an experimental methodology was developed to measure X-ray spectra in clinical mammography devices. Then, the following methods for calculating the DgNp using these spectra were considered: Method I, which calculates the DgNp using the incident spectra; Method II, which uses incident and transmitted spectra by the bTEMs, and Method III, which uses incident and transmitted spectra to estimate the dose distributions in depth of the breast equivalent materials. Finally, thermoluminescent dosimeters (TLDs) were used as a comparative method to evaluate DgNp distributions. The methodology developed for measuring spectra proved to be efficient for the proper positioning and alignment of the detector and, consequently, for the measurement of direct X-ray spectra. The experimental incident spectra showed good agreement with spectra simulated in similar conditions. The results showed well-defined trends (either linear or exponential) of the distributions of these coefficients (DgNp) regarding the analyzed parameters. The DgNp values presented an exponential decay with the bTEM thickness and linear decrease with the glandularity. In addition, these coefficients increase linearly with the increase of the HVL and, consequently, with the increase of the effective energy. From the distributions of DgNp (obtained by Method III) it was possible to estimate the DgNp in the whole breast with a maximum difference of 5.2% from the values obtained using the Method II. The variation of the DgNp with the depth, obtained with TLDs, showed to be consistent with the results observed using the Method III. In conclusion, it is possible to evaluate the glandular dose in mammography examinations using X-ray spectra and the suggested methodology, with some adaptations, can be applied as an alternative procedure for dosimetry in mammography.
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Nordqvist, Malin. "Modellering av byggnaders skyddskoefficienter vid utsläpp av radioaktiva ämnen." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-195665.

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I händelse av ett radioaktivt utsläpp är det viktigt att ha bra beredskap med skyddsåtgärder som bidrarmed det bästa skyddet för den utsatta delen av befolkningen. Direkt efter ett utsläpp utgör exponering viainandning det största problemet eftersom partiklar och gaser ännu inte hunnit deponerats på mark, imoln och så vidare. Byggnader bidrar med ett skydd mot inhalation eftersom luften utanför och inutibostaden byts ut relativt långsamt. Hur stor del av föroreningen som tar sig in till inomhusluften och hurlång tid detta tar är viktig information för att avgöra om befolkningen är tillräckligt skyddade inutibyggnader eller om evakuering bör ske. I detta arbete har kunskap från befintlig litteratur samtmodellering använts för att beskriva generella förhållanden med vilka en förorening kan ta sig in i och utur en byggnad. Differentialekvationer med huvudprocesser och ingående parametrar har studerats för attge en uppfattning om vilket skydd en byggnad kan ge mot inhalation av partiklar och gaser i ettradioaktivt moln. Olika typer av ventilationssystem med eller utan tillhörande partikelfilter diskuteras ochinhalationsdos för olika åldersklasser och aktivitetsnivåer undersöks.Genom att jämföra mängd förorening i luften utanför mot inuti en byggnad talar man om byggnadensskyddskoefficient. De tre huvudprocesser som styr transporten är ventilation, penetration samtdeponering. Ventilationen uppkommer av luftutbytet mellan inomhus‐ och utomhusluften. Ventilationenstyrs antingen mekaniskt eller naturligt. Penetrationen beskriver hur stor andel av partiklarna ellergaserna som tar sig in över byggnadens fasad och deponeringen hur partiklar och gaser tenderar attfastna på de ytor de passerar under transporten. Deponeringen sker även på samtliga ytor inutibyggnaden. Efter att ämnen deponerats kan de resuspendera och åter komma upp till luften vilketmöjliggör för inandning innan de åter kan deponera på tillgängliga ytor. Deponeringen ses som en sänkamedan resuspensionen fungerar som en källa för inomhuskoncentrationen.En av de faktorer som påverkar skyddskoefficienten till störst del är partikeldiametern eftersomdeponerings‐ och penetrationsprocessen är starkt storleksberoende. Stora och små partiklar deponeraslättare och kvar finns den så kallade mellanfraktionen, 0,2‐1 μm i diameter, som håller sig i luften längsttid. Gaser rör sig lätt in och ut ur byggnaden och hindras inte av partikelfilter. Däremot finns särskildafilter att installera som hindrar gaser att ta sig in, exempelvis kolfilter. Sönderfallshastigheten hos de olikaradionukliderna påverkar även skyddsfaktorn. Då ämnena sönderfaller minskar koncentrationen i luften,sönderfallet är då en sänka för koncentrationen inomhus. Ventilationshastigheten har en viss påverkan påskyddskoefficienten. En ökad ventilationshastighet leder till att koncentrationen inomhus kommer att gåmot penetrationsfaktorn. Detta gäller om ventilationshastigheten kan antas vara mycket större ändepositionshastigheten. Ventilationssystem utrustade med partikelfilter kan hålla en stor del avföroreningen utanför byggnaden. Partikelfiltren har olika effektivitet och klassificeras som grov‐, mediumsamtfinfilter. En hög filtereffektivitet har stor påverkan på skyddskoefficienten. Ett filter skall däremotses som en färskvara. De kräver underhåll och bör bytas ut i tid för att kunna fungera som de ska.Inhalationsdosen beror av partikelstorlek eftersom deponeringen som sker i luftvägarna fungerar påliknande sätt som i transporten in och ut ur byggnaden. Mellanfraktionen har tendens att tränga djupt nedi lungorna efter inandning. Effekten från inhalation beror på en individs ålder, storlek och fysisk aktivitet.<br>In case of a radioactive release, it is important to have good preparedness with the right actions to contribute the best protection for the vulnerable section of the population. Immediately after a release theexposure through inhalation will be the biggest problem, since particles and gases have not beendeposited on land, clouds and so on. Buildings contribute to protection against inhalation. The reason forthis is that the air outside and inside the dwelling is changed relatively slowly. How much of the pollutionthat enter the indoor air and how long time it takes is important information to determine if thepopulation is sufficiently protected inside buildings or if evacuation is needed. In this work knowledgefrom existing literature and modelling has been used to describe general conditions with which apollutant moves in and out of a building. Differential equations with main processes and parameters havebeen studied to give a estimation as to the protection a building can provide against exposure throughinhalation of particles and gases in a radioactive cloud. Different types of ventilation systems, with orwithout associated particle filter are discussed and inhalation dose for different age groups and activitylevels are examined.A buildings protection coefficient is defined by comparing the amount of pollution in the air outside withthe air inside a building. The three main processes that control the transport of the pollution in and outfrom a building are ventilation, penetration and deposition. Ventilation arises of air exchange betweenindoor and outdoor air. Ventilation is controlled either mechanically or naturally. Penetration describesthe proportion of the particles or gases that enter trough the buildings shell. Deposition of particles andgases accurse due to the fact that they tend to stick to the surfaces they pass in transit. The deposition alsooccurs on all surfaces inside the building. After the particles and gases have become deposited, they mayre‐suspend and come back up into the air permitting inhalation before they once more deposit onavailable surfaces. The deposit is seen as a sink while re‐suspension acts as a source for indoor airconcentration.One of the factors that have a large impact of a buildings protection factor is the particle diameter, due tothe deposition and penetration process strongly dependent on particles size. Large and small particlesdeposited easier and the remaining fraction, the midfraction (0.2 to 1 micron in diameter), remains. Thisfraction will stay in the air longer since the deposition process does not affect it strongly. Gases moveeasily in and out of the building and are not prevented by the particle filter. However, there are specialfilters to install that prevent gases to penetrate, such as carbon filters. The rate of decay of the variousradionuclides also affects the protection factor. When nuclides decay the concentration in the airdecreases, the decay is then a sink of the concentration indoors. Ventilation rate has a certain influence onprotection coefficient. An increased ventilation rate leads to the concentration inside approaching thepenetration factor; this is applied if the ventilation rate can be assumed to be much higher than thedeposit rate. Ventilation system equipped with a particle filter can keep a large part of the pollutantoutside the building. Particle filters have different efficiency and are classified as coarse, medium and finefilter. High filter efficiency has a major impact on the protection coefficient. For a filter to functionproperly it demands maintenance and should be replaced in time.Inhalation dose depends on the particle size, since the deposition process affected in respiratory functionis similar to the transport in and out of a building. The midfraction tends to penetrate deep into the lungsafter inhalation. The effect of inhalation is due to an individual's age, size, and physical activity.
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Cavalcante, Fernanda Rocha. "Simulação Monte Carlo de cenários de radiologia intervencionista pediátrica no código MCNPX." Universidade Federal de Sergipe, 2017. https://ri.ufs.br/handle/riufs/5271.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq<br>Interventional radiology consists of minimally invasive procedures guided by real-time X-ray imaging of a region of the patient to be diagnosed or treated. Since it is a practice that uses ionizing radiation, performing these procedures should follow the three basic principles of radioprotection, which are justification, optimization (medical exposure), and dose limitation (occupational exposure). Interventional procedures in children with congenital heart defects are justified by substituting other high-risk procedures. However, as these procedures are responsible for high doses in the patient and individuals occupationally exposed (IOE), it is important to evaluate the medical exposures of pediatric individuals due to a greater susceptibility to radiation damage in these individuals who present a rapid metabolism and closer proximity of the organs. In addition, the longer life expectancy in children allows more time for any harmful effects of radiation, such as cancer, to manifest. Because direct dose measurement within the human body is difficult or impractical, the Monte Carlo simulation of radiation transport is a useful tool in estimating dosimetric protection quantities (H T and E) in anthropomorphic phantoms representing the anatomy of the human body. In addition, it is possible to calculate conversion coefficients that relate protection quantities with measurable quantities, such as the kerma-area product (PKA). In this work, we modelled paediatric interventional cardiology scenarios using the MCNPX code and a pair of adult and paediatric hybrid anthropomorphic phantoms (newborn, 1 year and 5 year) to evaluate medical and occupational exposures. The results obtained in this work show conversion coefficients H T /PKA and E/PKA of 5 to 16 times higher than the values obtained in the literature for interventional procedures performed in adult patients. In addition, we estimate the influence of personal protective equipment (lead apron, thyroid shield and lead glasses) on occupational exposures, which contribute to reduction of H T doses in the physician up to 98% (gonads and thyroid), when used.<br>A radiologia intervencionista consiste de procedimentos minimamente invasivos guiados por imagens de raios X em tempo real de uma região do paciente a ser diagnosticada ou tratada. Por ser uma prática que utiliza radiação ionizante, a realização destes procedimentos deve seguir os três princípios básicos de radioproteção, que são a justificação, otimização (exposição do paciente) e limitação de dose (exposição do médico). Os procedimentos intervencionistas em crianças com cardiopatias congênitas são justificáveis por substituírem outros procedimentos de alto risco. Entretanto, conforme estes procedimentos são responsáveis por altas doses no paciente, além dos indivíduos ocupacionalmente expostos (IOE), é importante avaliar as exposições médicas de indivíduos pediátricos devido uma maior susceptibilidade de ocorrência de danos provocados pela radiação nestes indivíduos, que apresentam metabolismo rápido e maior proximidade anatômica dos órgãos. Além disso, a maior expectativa de vida das crianças induz uma maior probabilidade de ocorrência de efeitos estocásticos tardios como o câncer. Devido à medição direta da dose dentro do corpo humano ser difícil ou impraticável, a simulação Monte Carlo do transporte de radiação é uma ferramenta útil na estimativa de grandezas dosimétricas de proteção (H T e E) em simuladores antropomórficos que representam a anatomia do corpo humano. Além disso, é possível calcular coeficientes de conversão que relacionam grandezas de proteção com grandezas mensuráveis, como o produto kerma-área (PKA). Neste trabalho, modelamos cenários de cardiologia intervencionista pediátrica utilizando o código MCNPX e uma dupla de simuladores antropomórficos híbridos adulto e pediátrico (recém-nascido, de 1 e 5 anos) para avaliar as exposições médicas e ocupacionais. Os resultados obtidos neste trabalho mostram coeficientes de conversão H T /PKA e E/PKA de 5 a 16 vezes maiores que os valores obtidos na literatura para procedimentos intervencionistas realizados em pacientes adultos. Além disso, estimamos a influência dos equipamentos de proteção individual (avental, óculos plumbíferos e protetor de tireoide) nas exposições ocupacionais, que contribuem para redução das doses H T no médico em até 98% (gônadas e tireoide), quando utilizados.
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Hernandes, Fabiano. "Unsteady aerodynamic coefficients obtained by a compressible vortex lattice method." Instituto Tecnológico de Aeronáutica, 2009. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=954.

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Unsteady solutions for the aerodynamic coefficients of a thin airfoil in compressible subsonic or supersonic flows are studied. The lift, the pitch moment, and pressure coefficients are obtained numerically for the following motions: the indicial response (unit step function) of the airfoil, i.e., a sudden change in the angle of attack; a thin airfoil penetrating into a sharp edge gust (for several gust speed ratios); a thin airfoil penetrating into a one-minus-cosine gust and sinusoidal gust (a typical gust used in commercial aircraft design); oscillating airfoil; and also the interaction of the airfoil with a shed (from convection phenomenon) vortex passing under the airfoil, a phenomenon known in literature as AVI (Airfoil Vortex Interaction). The present work uses a numerical approach based on vortex singularity. The numerical model is created by means of the airfoil discretization in uniform segments and the compressible flow vortex singularity is used. The results available in the literature are based on approximated exponential equations, or computed via Computational Fluid Dynamics (CFD). Thus, the purpose of this method is to obtain a more accurate computation compared to those of approximated equations, and numerically quite faster compared to those obtained via CFD.
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Tomal, Alessandra. "Medidas experimentais dos coeficientes de atenuação de tecidos mamários e sua influência no contraste e dose mamográfica." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-12092007-082142/.

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O estudo e a determinação das propriedades de atenuação de tecidos mamários são fundamentais para o entendimento e para a quantificação do contraste e da dose absorvida em um exame mamográfico. A proposta deste trabalho é determinar experimentalmente os coeficientes de atenuação de tecidos mamários e, posteriormente, incorporar esses resultados a um modelo teórico-analítico que possibilite o estudo da influência de diversos parâmetros no contraste de objetos e na dose em mamografia. Dentre os fatores de estudo, destacam-se as características da mama (geometria e composição), a técnica radiográfica, a combinação ânodo-filtro e o receptor de imagem. Os coeficientes de atenuação foram medidos usando geometria de feixe estreito, no intervalo de energia entre 8 e 30 keV, utilizando um difratômetro de raios-X 4-círculos P3 Nicolet-Siemens e um monocromador de Si (111). Para essas medidas foram utilizadas 63 amostras de tecidos mamários (classificadas previamente como tecidos normais, fibroadenomas e/ou diferentes tipos de carcinomas). Os coeficientes de atenuação medidos foram comparados com predições teóricas, obtidas usando a regra das misturas, e com dados experimentais previamente publicados. O modelo desenvolvido para o contraste objeto leva em conta as contribuições primária e secundária na radiação transmitida. A dose média absorvida foi estimada através de duas aproximações, que permitem predizer os limites superior e inferior, e de uma aproximação mais completa, que inclui as componentes espalhadas simples e duplas. O modelo desenvolvido neste trabalho permite a obtenção de resultados de forma simples e rápida, com valores similares aos obtidos por simulação Monte Carlo, bem como definir limites de detecção de massas tumorais.<br>The study and determination of attenuation properties of breast tissues are fundamental to understand and quantify contrast and absorbed dose in the mammographic examination. The purpose of this work is to experimentally determine the attenuation coefficient of breast tissues, and then to include these results into a theoretical analytical model, in order to study the influence of several parameters on subject contrast and dose in mammography. Among the parameters studied, one can emphasize the breast characteristics (geometry and composition), the radiographic technique, the target-filter combination and the image receptor. The attenuation coefficients were measured using narrow beam geometry, within the energy range of 8-30 keV, using an x-ray diffractometer 4-circle P3 Nicolet-Siemens and a monocromator of Si (111). For these measurements were analyzed 63 breast tissue samples (previously classified as normal tissues, fibroadenomas and several types of carcinomas). The linear attenuation coefficients measured were compared with theoretical predictions obtained from the mixture rule, and with experimental data previously published. The developed model to the subject contrast takes into account the primary and scattered contribution of the transmitted radiation. The average absorbed dose was estimated considering two simplified approaches, which allowed to predict upper and lower limit values, and a more complete approach, which included the contribution of single and double scattered radiation. The analytical model developed in this work provided results in a fast and simple way, with a good agreement with those reported by others authors who had used Monte Carlo simulation, as well it allowed to define limit values for detection of tumor masses.
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Sêcco, Ney Rafael. "Training artificial neural networks to predict aerodynamic coefficients of airliner wing-fuselage configurations." Instituto Tecnológico de Aeronáutica, 2014. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2955.

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Multi-disciplinary Design Optimization highly demands computational resources, therefore it is important to develop design tools with low computational cost without compromising the fidelity of the model. The main goal of this work was to establish a methodology of training artificial neural networks for specific purposes of aircraft aerodynamic design, in order to substitute a computational fluid dynamics software in an optimization framework. This neural network would predict the lift and drag coefficients for an airliner';s wing-fuselage configuration based on its planform, airfoil, and flight condition parameters. This work also aimed to find the structure and the size of the network that best suits this problem, setting up references for future works. The aerodynamic database required for the neural network training was generated with a full-potential multiblock code. The training used the back propagation algorithm, the scaled conjugate gradient algorithm, and the Nguyen-Widrow weight initialization. Networks with different numbers of neurons were evaluated in order to minimize the regression error. The optimum networks reduced the computation time for the calculations of the aerodynamic coefficients in 4000 times when compared with the full-potential code. The average absolute errors obtained were of 0.004 and 0.0005 for lift and drag coefficients, respectively. We also propose an adapted version of the back propagation algorithm that allows the computation of gradients for optimization tasks using the artificial neural networks.
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Omerdin, Khadijah. "Does Depreciation Matter to Investors?" Scholarship @ Claremont, 2017. http://scholarship.claremont.edu/cmc_theses/1692.

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This paper will analyze the usefulness of depreciation expense to investors. Depreciation expense is a broad allocation accounting practice that treats different types of assets the same. I argue that there are two types of industries: those with wasting assets, and those with real property. The first type experiences true deprecation and deterioration while the second type of asset does not. A simplified model using the earnings response coefficient will measure the relationship between earnings and returns for these different industries; this measurement is a way to quantify usefulness of accounting information. I hypothesize that investors of companies with high wasting assets will find depreciation more useful than those invested in companies with more real property. However, the results were not consistent with my hypothesis – depreciation did not matter more to investors of the industry with high wasting assets. The data set only included two distinct industries, which limited the sample size considerably, and might explain the results. Alternatively, the two groups of assets could be defined more broadly to include more industries for future research.
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Books on the topic "Dose coefficients"

1

Guide to Dose Coefficients. National Radiological Protection Board, 2001.

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ICRP. ICRP CD2: Database of Dose Coefficients--Embryo and Fetus. Elsevier, 2002.

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ICRP. ICRP CD2: Database of Dose Coefficients--Embryo and Fetus. Elsevier, 2002.

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ICRP. ICRP Publication 68: Dose Coefficients for Intakes of Radionuclides by Workers. Elsevier, 1995.

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ICRP. The ICRP Database of Dose Coefficients: Workers and Members of the Public. PERGAMON PRESS, 1999.

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ICRP. The ICRP Database of Dose Coefficients: Workers and Members of the Public. Elsevier, 2001.

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Staff, ICRP. ICRP Publication 136: Dose Coefficients for Non-Human Biota Environmentally Exposed to Radiation. SAGE Publications, Limited, 2017.

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ICRP. ICRP Publication 69: Age-dependent Doses to Members of the Public from Intake of Radionuclides: Part 3 Ingestion Dose Coefficients. Elsevier, 1995.

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ICRP. ICRP Publication 71: Age-dependent Doses to Members of the Public from Intake of Radionuclides: Part 4 Inhalation Dose Coefficients. Elsevier Science Publishing Company, 1996.

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ICRP. ICRP Publication 67: Age-dependent Doses to Members of the Public from Intake of Radionuclides: Part 2 Ingestion Dose Coefficients. Elsevier, 1994.

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Book chapters on the topic "Dose coefficients"

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Hertel, Nolan E., and Derek Jokisch. "Dose Coefficients." In Advanced Radiation Protection Dosimetry. CRC Press, 2019. http://dx.doi.org/10.1201/9780429055362-8.

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Melintescu, A., D. Galeriu, and H. Takeda. "Reassessment of Tritium Dose Coefficients." In Survival and Sustainability. Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-95991-5_56.

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Han, Haegin, Yeon Soo Yeom, Chansoo Choi, et al. "Dose Coefficients for Use in Rapid Dose Estimation in Industrial Radiography Accidents." In Brain and Human Body Modeling. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-21293-3_15.

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Sarno, Antonio, Giovanni Mettivier, Francesca Di Lillo, and Paolo Russo. "Monte Carlo Evaluation of Normalized Glandular Dose Coefficients in Mammography." In Breast Imaging. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-41546-8_25.

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Dimov, Asen, Ivan Tsanev, and Dimitar Penev. "Technique and Gender Specific Conversion Coefficients for Estimation of Effective Dose from Kerma Area Product During X-Ray Radiography of Chest." In IFMBE Proceedings. Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-9035-6_133.

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Lechner, Bernhard, Almir Cajic, Bernhard Fischbacher, et al. "Validation of Truck Platoon Slipstream Effects." In Energy-Efficient and Semi-automated Truck Platooning. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-88682-0_6.

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AbstractDue to slipstream effects, platooning leads to a significant decrease of the fuel consumption of the heavy-duty vehicles (HDV). Measurements with a platoon consisting of three vehicles were performed at the Zalazone proving ground. The goal of these measurements was to get the static pressure at the front and the rear of the second vehicle to calibrate computational fluid dynamics simulation and to measure the fuel consumption directly. Measurements were done at a vehicle speed of 80 km/h and varying inter-vehicle distances. Platooning leads to a reduction of the pressure coefficients in the centre of the HDV front and an increase of the pressure coefficient at the top and the rear of the HDV. Furthermore, a reduction of the fuel consumption of the leading vehicle of 7.9% at an inter-vehicle distance of 6 m and 3.7% at a distance of 22 m was determined. A comparison to CFD simulation showed a similar fuel reduction for an inter-vehicle distance of 6 m and 22 m. CFD simulation showed an increase of fuel consumption at an inter-vehicle distance of 15 m. This increase was experimentally not validated. Also, results for the following vehicle are presented.
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Gazdag, András, György Lupták, and Levente Buttyán. "Correlation-Based Anomaly Detection for the CAN Bus." In Communications in Computer and Information Science. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-09357-9_4.

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AbstractPrevious attacks have shown that in-vehicle networks have vulnerabilities and a successful attack could lead to significant financial loss and danger to life. In this paper, we propose a Pearson correlation based anomaly detection algorithm to detect CAN message modification attacks. The algorithm does not need a priori information about the communication: it identifies signals based on statistical properties, finds the important correlation coefficients for the correlating signals, and detects attacks as deviations from a previously learned normal state.
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Croccolo, Dario, Rossano Cuppini, and Nicolò Vincenzi. "Friction Coefficients Definition in Compression-Fit Couplings Applying the Doe Method." In Experimental Analysis of Nano and Engineering Materials and Structures. Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6239-1_220.

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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Thermal Wave Nonreciprocity: Angular Momentum Bias." In Transformation Thermotics and Extended Theories. Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_20.

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AbstractIn this chapter, we demonstrate that an angular momentum bias generated by a volume force can also lead to modal splitting in convection-diffusion systems but with different features. We further reveal the thermal Zeeman effect by studying the temperature field propagation in an angular-momentum-biased ring with three ports (one for input and two for output). With an optimal volume force, temperature field propagation is allowed at one output port but isolated at the other, and the rectification coefficient can reach a maximum value of 1. The volume forces corresponding to the rectification coefficient peaks can also be quantitatively predicted by scalar (i.e., temperature) interference. Compared with existing mechanisms for thermal nonreciprocity, an angular momentum bias does not require temperature-dependent and phase-change materials, which has an advantage in wide-temperature-range applicability. These results may provide insights into thermal stabilization and thermal topology. The related mechanism is also universal for other convection-diffusion systems such as mass transport, chemical mixing, and colloid aggregation.
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Yousef, Majdi A. A., and R. Panneer Selvam. "Compare Tornado Force Coefficients on Dome and Prism Building Using Three-Dimensional Computational Fluid Dynamics Model." In Lecture Notes in Mechanical Engineering. Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-5329-0_18.

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Conference papers on the topic "Dose coefficients"

1

Schlattl, Helmut. "Dose conversion coefficients for partial-fan CBCT scans." In SPIE Medical Imaging, edited by Thomas G. Flohr, Joseph Y. Lo, and Taly Gilat Schmidt. SPIE, 2017. http://dx.doi.org/10.1117/12.2250571.

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Fruit, Michel, Andrei I. Gusarov, Dominic B. Doyle, and Gerd J. Ulbrich. "Radiation impact on spaceborne optics: the dose coefficients approach." In Remote Sensing, edited by Edward W. Taylor and Francis Berghmans. SPIE, 1999. http://dx.doi.org/10.1117/12.373286.

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Liu, Fangfang, Mingqi Shen, Taosheng Li, and Chunyu Liu. "Proton Dose Conversion Coefficients Based on Chinese Reference Adult Woman Voxel Phantom." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-15506.

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In order to calculate the dose conversion coefficients for proton, the voxel model of Chinese Reference Adult Woman (CRAW) was established by the Monte Carlo transport code FLUKA according to the Chinese reference data and the Asian reference data. Compared with the reference data, the deviations of the mass for organs or tissues of CRAW is less than ±5%. Calculations have been performed for 14 incident monoenergetic protons energies from 0.02GeV to 10TeV at the irradiation incident of anterior-posterior (AP) and posterior-anterior (PA). The results of fluence-to-effective dose conversion coefficients are compared with data from the different models such as an anthropomorphic mathematical model, ICRP reference adult voxel model, the voxel-based visible Chinese human (VCH). Anatomical differences among various computational phantoms and the spatial geometric positions of the organs or tissues lead to the discrepancies of the effective dose conversion coefficients in the ranging from a negligible level to 107% at proton energies below 0.2GeV. The deviations of the coefficients, above 0.2GeV, are mostly within 10%. The results of fluence-to-organ absorbed dose conversion coefficients are compared with the data of VCH. The deviations of the coefficients, below and above 0.2GeV, are within 150% and 20%, respectively. The primary factors of the deviations for the coefficients should be due to the differences of the organ mass and the size of the body shape.
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Fruit, Michel, Andrei I. Gusarov, Dominic B. Doyle, Gerd J. Ulbrich, and Alex Hermanne. "Space radiation sensitivity of glasses: first results toward a comprehensive dose coefficients database." In International Symposium on Optical Science and Technology, edited by Edward W. Taylor. SPIE, 2000. http://dx.doi.org/10.1117/12.405352.

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Fu, Wanyi, Xiaoyu Tian, Pooyan Sahbaee, Yakun Zhang, William Paul Segars, and Ehsan Samei. "Organ dose conversion coefficients for tube current modulated CT protocols for an adult population." In SPIE Medical Imaging, edited by Despina Kontos, Thomas G. Flohr, and Joseph Y. Lo. SPIE, 2016. http://dx.doi.org/10.1117/12.2217271.

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Schlattl, Helmut, Maria Zankl, and Christoph Hoeschen. "CTDIvol: a suitable normalization for CT dose conversion coefficients at different tube voltages?" In SPIE Medical Imaging, edited by Norbert J. Pelc, Robert M. Nishikawa, and Bruce R. Whiting. SPIE, 2012. http://dx.doi.org/10.1117/12.910905.

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Choi, Jang-Hwan, Dragos Constantin, and Rebecca Fahrig. "A numerical investigation for the optimal positions and weighting coefficients of point dose measurements in the weighted CTDI." In SPIE Medical Imaging, edited by Christoph Hoeschen, Despina Kontos, and Thomas G. Flohr. SPIE, 2015. http://dx.doi.org/10.1117/12.2082477.

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Kalinin, V. N., and V. N. Zabrotski. "ESTIMATION OF HEALTH RISK FOR PERSON CONSUMING BUSHMEAT TAKEN AT THE CHERNOBYL EXCLUSION ZONE." In SAKHAROV READINGS 2021: ENVIRONMENTAL PROBLEMS OF THE XXI CENTURY. International Sakharov Environmental Institute of Belarusian State University, 2021. http://dx.doi.org/10.46646/sakh-2021-2-263-266.

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According to the gamma-spectrometry analysis measurements of the bushmeat samples taken by hunters in exclusion zone 137Cs activity concentration could reach the value of 3 kBq/kg. The probable effective doses of the internal irradiation of the bushmeat consumers were calculated according to the consumer basket and using the dose coefficients (dose per unit exposure). In case of the consumption of the bushmeat that meets the hygienic level the radiation risk of cancer mortality will not exceed the value of the generalised risk equal 1,0*10-5 year-1 for the population.
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Sanders, Charlotta E. "Development of Buildup Factors for Updating the ANSI/ANS-6.4.3 Standard." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-30212.

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The ANSI/ANS-6.4.3-1991 Standard, Gamma-Ray Attenuation Coefficients and Buildup Factors for Engineering Materials, is currently being updated by an American Nuclear Society (ANS) Working Group. The ANSI/ANS-6.4.3, 1991 standard, which is “withdrawn” due to the failure to meet the requirement of the ANS to have standards updated every ten years, contains buildup factor values that are derived from data that is over seventeen years old. In addition, computer technology has significantly improved since 1991, allowing for more complicated, computationally demanding codes to be utilized. Therefore, the ANSI/ANS-6.4.3-1991 standard is being re-visited to include updated data and to include modern codes. Gamma-ray buildup factors and attenuation coefficients are being generated for common shielding materials (e.g., concrete, steel, water, etc.) utilizing the ENDF/B-VI.8 cross-section data library, which is distributed by Brookhaven National Laboratory’s National Nuclear Data Center (NNDC). One modern code, Monte Carlo N-Particle (MCNP5/MCNPX), is being compared with PALLAS-1D (VII) and Anisotropic Source-Flux Iteration Technique (ASFIT-VARI), which were used to develop values included in ANSI/ANS-6.4.3-1991. PALLAS-1D (VII) is a code for direct integration of transport equation in one-dimensional plane and spherical geometries while ASFIT-VARI is a gamma-ray transport code system for one-dimensional finite systems. MCNP5 is a general purpose Monte Carlo radiation transport code that tracks particles (e.g., neutron and photons) at numerous energies in a three dimensional configuration of materials. The MCNP5 radiation transport code require response function input to provide dose and exposure output. Mass energy-absorption coefficients and mass energy-transfer coefficients are required to develop absorbed dose and exposure responses. The National Institute of Standards and Technology (NIST) provide and maintain the most up-to-date mass energy-absorption coefficient and mass energy-transfer coefficient database currently available. The NIST values are used in these initial buildup factor calculations to prove the validity of the methodology used and allow for preliminary comparisons. The energy absorption (dose in material) and exposure buildup factors are calculated at mfp values of interest, consistent with ANSI/ANS-6.4.3-1991 up to forty mfp. Comparisons between the new buildup factors and the previous results presented in the ANSI/ANS-6.4.3-1991 standard indicate that there is fairly good agreement. Differences in buildup factor values can be attributed to differences in cross-section data libraries, numerical methods, and physics treatments within the respective codes.
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Backfrieder, Werner. "A multi-modal data model for morphological segmentation in 3D dosimetry." In the 8th International Workshop on Innovative Simulation for Healthcare. CAL-TEK srl, 2019. http://dx.doi.org/10.46354/i3m.2019.iwish.004.

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"Patient specific dosimetry established during the last decade in modern radio-therapy. Usually, tracer kinetics in main compartments of observed metabolism is assessed from anterior and posterior whole body scans. The effective doses for each organ, derived by the MIRD scheme, provide evidence for following radiotherapeutic treatment and helps to meet vital dose limits for critical organs, e.g. kidneys. The calculation of individual dose in a three-dimensional context leads to more accurate dose estimates, as was proven by intensive research, but is still on the cusp to clinical application. In this work, a statistical approach, based on multi-modal image and feature data, is presented, to overcome manual segmentation, the most time consuming step, in 3D based dose calculation. 3D data volumes from a hybrid SPECT study, comprising SPECT and CT data, covering main compartments of metabolism, build the image features of a Gaussian classifier. From prior segmentations organspecific membership maps are derived, and substituted as additional feature into the segmentation procedure. Centroids, eccentricity and principal axes of organ models are registered to a rough thresholded image of the SPECT component, and define membership coefficients of the voxels. The new approach yields accurate results, even with real patient data. The new method needs minimal user interaction during selection of some sample regions, thus showing high potential for implementation in a clinical workflow."
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Reports on the topic "Dose coefficients"

1

Jannik, Tim. UPDATED EXTERNAL EXPOSURE DOSE COEFFICIENTS. Office of Scientific and Technical Information (OSTI), 2020. http://dx.doi.org/10.2172/1632841.

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Kocher, D. C., and K. F. Eckerman. On the use of age-specific effective dose coefficients in radiation protection of the public. Office of Scientific and Technical Information (OSTI), 1998. http://dx.doi.org/10.2172/676937.

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Blanchard, A. Derived Intervention Levels for Tritium Based on Food and Drug Administration Methodology Using ICRP 56 Dose Coefficients. Office of Scientific and Technical Information (OSTI), 1999. http://dx.doi.org/10.2172/7962.

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Eckerman, K. F., and R. W. Leggett. DCFPAK: Dose coefficient data file package for Sandia National Laboratory. Office of Scientific and Technical Information (OSTI), 1996. http://dx.doi.org/10.2172/419124.

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Saarnio, Karri, Mika Vestenius, and Katriina Kyllönen. Attestation of conformity of particulate matter measurements (HIVATO) 2019–2020. Finnish Meteorological Institute, 2021. http://dx.doi.org/10.35614/isbn.9789523361331.

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The National Reference Laboratory for Air Quality (NRL) ensures the high quality of air quality measurements in Finland by organising audits and intercomparison campaigns. In this project, the conformity of the particulate matter measurements was evaluated with a particular focus on the measurement used for calculating the average exposure index (AEI) of Finland. The representativity and applicability of the AEI measurements made at the Kallio station in Helsinki were evaluated. It was noticed that the results of the Kallio measurement represent well the average fine particle (PM2.5) concentrations and the yearly based trend of fine particles in Finland. In addition, the yearly average concentrations of fine particles have been smaller than the AEI limit value of 8.5 µg/m3, at all individual urban background stations in Finland since year 2015. The measurement results made with the PM monitor used for AEI measurement, i.e. TEOM 1405 analyser at the Kallio station, were compared to the results from the reference method that follows the standard SFS-EN 12341:2014. It was noticed that the uncertainty requirement of 25% was reached and therefore the quality of the measurement is sufficient to use it for the calculation of AEI. However, the fine particle concentrations were generally very low and therefore the requirements given in the standard SFS-EN 16450:2017 for an intercomparison against the reference method were not perfectly fulfilled. This report presents also results from intercomparison measurements made for automated continuous measurement systems (AMS). At the Virolahti station and at the Mäkelänkatu station in Helsinki, PM10 and PM2.5 measurements were compared. In Kuopio and in Lahti, intercomparison measurements were made for PM2.5 only. Based on the results from these intercomparisons, the calibration coefficients both for PM10 and PM2.5 were defined for the first time in Finland for a FIDAS 200 analyser that is a new PM monitor in the Finnish market. It was concluded that FIDAS 200 analysers can be used for the PM measurements in Finland when the calibration coefficients are applied for the data; however, one must note that the presented calibration coefficients do not fulfil the requirements given for the demonstration of equivalence (DoE). Nevertheless, these coefficients are recommended to be used until the official coefficients will be delivered from the next DoE campaign. Two AMS (SHARP 5030 and TEOM 1405) were compared to the reference method for the measurements of PM10 and PM2,5 in Virolahti and in Helsinki, respectively. It was revealed that the calibration coefficients based on the DoE in Kuopio (2014–2015) do not always fit ideally at different locations and seasons due to differences in the environmental characteristics of the measurement sites. Therefore, NRL recommends that DoE should be organised every five years and in between the DoE’s so called ongoing-intercomparison measurements should be carried out continuously. In the ongoing-intercomparison, suitability of the calibration coefficients from DoE will be verified in different locations with varying environmental characteristics. The ongoing-intercomparison campaigns should take place at one site from a half a year to one year and after that, the campaign should continue at a different location similarly. This would ensure that the influence of seasonal differences to the suitability of coefficients will be verified at each measurement site.
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MIRKINA, O. ANALYTICAL COEFFICIENTS IN THE EVALUATION OF THE ACTIVITIES OF MICROENTERPRISES. Science and Innovation Center Publishing House, 2021. http://dx.doi.org/10.12731/2070-7568-2021-10-6-1-28-33.

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Analysis and evaluation of the company’s activities allow you to make informed management decisions. Microenterprises make up several forms of reporting, which does not allow for a full-fledged analysis. It is necessary to identify a group of analytical coefficients that will characterize the social, economic and financial condition of a microenterprise.
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Sullivan, T. Recommended values for the distribution coefficient (Kd) to be used in dose assessments for decommissioning the Zion Nuclear Power Plant. Office of Scientific and Technical Information (OSTI), 2014. http://dx.doi.org/10.2172/1143601.

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Sullivan, T. Recommended values for the distribution coefficient (Kd) to be used in dose assessments for decommissioning the Zion Nuclear Power Plant. Office of Scientific and Technical Information (OSTI), 2014. http://dx.doi.org/10.2172/1178623.

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Goetsch, Arthur L., Yoav Aharoni, Arieh Brosh, et al. Energy Expenditure for Activity in Free Ranging Ruminants: A Nutritional Frontier. United States Department of Agriculture, 2009. http://dx.doi.org/10.32747/2009.7696529.bard.

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Heat production (HP) or energy expenditure for activity (EEa) is of fundamental nutritional importance for livestock because it determines the proportion of ingested nutrients available for productive functions. Previous estimates of EEa are unreliable and vary widely with different indirect methodologies. This leads to erroneous nutritional strategies, especially when intake on pasture does not meet nutritional requirements and supplementation is necessary for acceptable production. Therefore, the objective of this project was to measure EEa in different classes of livestock (beef cattle and goats) over a wide range of ecological and management conditions to develop and evaluate simple means of prediction. In the first study in Israel, small frame (SF) and large frame (LF) cows (268 and 581 kg) were monitored during spring, summer, and autumn. Feed intake by SF cows per unit of metabolic weight was greater (P &lt; 0.001) than that by LF cows in both spring and summer and their apparent selection of higher quality herbage in spring was greater (P &lt; 0.10) than that of LF cows. SF cows grazed more hours per day and walked longer distances than the LF cows during all seasons. The coefficient of specific costs of activities (kJ•kg BW-0.75•d-1) and of locomotion (J•kg BW-0.75•m-1) were smaller for the SF cows. In the second study, cows were monitored in March, May, and September when they grazed relatively large plots, 135 and 78 ha. Energy cost coefficients of standing, grazing, and horizontal locomotion derived were similar to those of the previous study based on data from smaller plots. However, the energy costs of walking idle and of vertical locomotion were greater than those found by Brosh et al. (2006) but similar to those found by Aharoni et al. (2009). In the third study, cows were monitored in February and May in a 78-ha plot with an average slope of 15.5°, whereas average plot slopes of the former studies ranged between 4.3 and 6.9°. Energy cost coefficients of standing, grazing, and walking idle were greater than those calculated in the previous studies. However, the estimated energy costs of locomotion were lower in the steeper plot. A comparison on a similar HP basis, i.e., similar metabolizable energy (ME) intake, shows that the daily energy spent on activities in relation to daily HP increased by 27% as the average plot slope increased from 5.8 and 6.02 to 15.5°. In the fourth study, cows grazing in a woodland habitat were monitored as in previous studies in December, March, and July. Data analysis is in progress. In the first US experiment, Boer and Spanish does with two kids were used in an experiment beginning in late spring at an average of 24 days after kidding. Two does of each breed resided in eight 0.5-ha grass/forb pastures. Periods of 56, 60, 63, 64, and 73 days in length corresponded to mid-lactation, early post-weaning, the late dry period, early gestation, and mid-gestation. EEa expressed as a percentage of the ME requirement for maintenance plus activity in confinement (EEa%) was not influenced by stocking rate, breed, or period, averaging 49%. Behavioral activities (e.g., time spent grazing, walking, and idle, distance traveled) were not highly related to EEa%, although no-intercept regressions against time spent grazing/eating and grazing/eating plus walking indicated an increase in EEa% of 5.8 and 5.1%/h, respectively. In the second study, animal types were yearling Angora doeling goats, yearling Boer wether goats, yearling Spanish wether goats, and Rambouilletwether sheep slightly more than 2 yr of age. Two animals of each type were randomly allocated to one of four pastures 9.3, 12.3, 4.6, and 1.2 ha in area. The experiment was conducted in the summer with three periods, 30, 26, and 26 days in length. EEa% was affected by an interaction between animal type and period (Angora: 16, 17, and 15; Boer: 60, 67, and 34; Spanish: 46, 62, and 42; sheep: 22, 12, and 22% in periods 1, 2, and 3, respectively (SE = 6.1)). EEa% of goats was predicted with moderate accuracy (R2 = 0.40-0.41) and without bias from estimates of 5.8 and 5.1%/h spent grazing/eating and grazing/eating plus walking, respectively, determined in the first experiment; however, these methods were not suitable for sheep. These methods of prediction are simpler and more accurate than currently recommended for goats by the National Research Council.
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10

Cao Romero, Julio A., Jorge Reyes-Avendaño, Julio Soriano, Leonardo Farfan-Cabrera, and Ali Erdemir. A Pin-on-Disc Study on the Electrified Sliding Wear of EVs Powertrain Gears. SAE International, 2022. http://dx.doi.org/10.4271/2022-01-0320.

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In contrast to conventional powertrains from internal combustion engine vehicles (ICEV), the tribological performance of powertrains of electric vehicles (EVs) must be further evaluated by considering new critical operating conditions such as electrical environments. The operation of any type of electric motor produces shaft voltages and currents due to various hardware configurations and factors. Furthermore, the common application of inverters intensifies this problem. It has been reported that the induced shaft voltages and currents can cause premature failure problems in tribological components such as bearings and gears due to accelerated wear and/or fatigue. It is ascribed to effects of electric discharge machining (EDM), also named, sparking wear caused by shaft currents and poor or increasingly diminishing dielectric strength of lubricants. A great effort has been done to study this problem in bearings, but it has not yet been the case for gears. Considering that EVs powertrains can be configurated with an electric motor coupled to a single-speed or multi-speed transmission, it is expected that shaft currents can also affect gears to some extent. The pin-on-disc test has been widely used to study sliding wear of gear materials under comparable or realistic operating conditions. This accelerated test is effective for screening materials, lubricants and operating conditions allowing evaluations of their friction and wear properties. However, it has not been implemented for studying gear materials under electrified environments. Thus, this paper aims to explore the friction coefficient and wear of gear materials under non-electrified and electrified sliding in a pin-on-disc tester applying typical of EVs powertrain shaft currents during sliding. The tests were carried out at two different DC currents under comparable gear dry and lubricated sliding contact conditions. Friction coefficient, wear volumes and morphologies were evaluated and reported in this work.
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