Rack Distribution Effects on MPLM Center of Mass

This research was in support of exploring the need for more flexible "center of gravity (CG) specifications than those currently established by NASA for the Multi-Purpose Logistics Module (MPLM). The MPLM is the cargo carrier for International Space Station (ISS) missions. The MPLM provides locations for 16 standard racks, as shown in Figure 1; not all positions need to be filled in any given flight. The MPLM coordinate system (X(sub M), Y(sub M), Z(sub M)) is illustrated as well. For this project, the primary missions of interest were those which supply the ISS and remove excess materials on the return flights. These flights use a predominate number of "Resupply Stowage Racks" (RSR) and "Resupply Stowage Platforms" (RSP). In these two types of racks, various smaller items are stowed. Hence, these racks will exhibit a considerable range of mass values as well as a range as to where their individual CG are located

Cofinement, entropy, and single-particle dynamics of equilibrium hard-sphere mixtures

We use discontinuous molecular dynamics and grand-canonical transition-matrix Monte Carlo simulations to explore how confinement between parallel hard walls modifies the relationships between packing fraction, self-diffusivity, partial molar excess entropy, and total excess entropy for binary hard-sphere mixtures. To accomplish this, we introduce an efficient algorithm to calculate partial molar excess entropies from the transition-matrix Monte Carlo simulation data. We find that the species-dependent self-diffusivities of confined fluids are very similar to those of the bulk mixture if compared at the same, appropriately defined, packing fraction up to intermediate values, but then deviate negatively from the bulk behavior at higher packing fractions. On the other hand, the relationships between self-diffusivity and partial molar excess entropy (or total excess entropy) observed in the bulk fluid are preserved under confinement even at relatively high packing fractions and for different mixture compositions. This suggests that the partial molar excess entropy, calculable from classical density functional theories of inhomogeneous fluids, can be used to predict some of the nontrivial dynamical behaviors of fluid mixtures in confined environments.Comment: submitted to JC

The Effects of Caffeinated Gum and Caffeine Capsules on Running Sprint Performance

Use of anhydrous caffeine is an established and widely used ergogenic method. In sprinting events, optimum performance is highly dependent on the simultaneous peak functioning of a host of physiological systems. Therefore, caffeine supplementation protocols need to be perfectly timed in order to achieve culmination in sprint performance parameters within a narrow time window. Typically, caffeine capsules are ingested approximately 1 h before exercise however absorption rates may be highly variable. An alternative mode of ingestion is through caffeinated gum where caffeine is rapidly absorbed through the buccal mucosa. Our aim was to investigate the acute effects of two distinct modes of caffeine ingestion on sprint performance. Following ethics approval, eight trained male sprinters aged 20.2 (±0.8) took part in a screening and familiarisation session before they completed four trials (3x40 m sprints with 4 min recovery between runs) a week apart. A double-blind randomized crossover design was adopted where, during the trials, participants received: 1) Caffeine gum (CAFG, 6 mg.kg-1 of body weight), 2) CAFG placebo (CAFGP), 3) Caffeine capsules (CAFC, mg.kg-1 of body weight), 4) CAFC placebo (CAFCP). General and sport-specific warm-up commenced 15 minutes before sprint one. Capsules were given 45 minutes and chewing gums 15 minutes before sprint one. The gums were chewed for 5 minutes. Blood lactate and glucose concentration, heart rate, arousal and feeling levels were recorded at baseline and different time points during testing. Mean time to complete the three sprints were 5.00(±0.23), 5.03(±0.17), 5.10(±0.15), and 5.10(±0.14) seconds for the CAFG, CAFC, CAFGP and CAFCP conditions respectively. Participants ran significantly faster (p<0.05) during the caffeine compared to the placebo conditions. Additionally, sprint two in the CAFG (2.25±0.45 % faster than CAFGP) was significantly faster (p=0.022) than in the CAFC (1.40±0.32 % faster than CAFCP). Blood glucose and arousal levels were also significantly higher during the caffeine trials. Our data confirms that caffeine is an effective ergogenic strategy for sprinters. Furthermore, the greatest performance gains in sprint two suggests that caffeinated gum may be a more efficacious mode of ingestion than traditional methods of caffeine ingestion

The Wool ComfortMeter and the Wool HandleMeter, new opportunities for wool

Two instruments have been developed by the Sheep CRC that provide the tools for a new standard in comfort and handle for the next generation of next-to-skin wool knitwear. The Wool ComfortMeter and Wool HandleMeter provide a rapid, accurate and objective measure of two important characteristics of wool knitwear that are currently determined by subjective assessment. The Wool HandleMeter allows the prediction of a set of handle attribute values that can quantify the hand feel of a lightweight jersey fabric. The instrument uses the principle of pushing a fabric sample through a ring. The force displacement curve associated with the fabric test is characterised and used to define each fabric. These values were then compared to the average handle values, as determined by a group of experts, of a large set of lightweight knitted fabrics. Algorithms were developed that enable the instrument to more accurately predict each of seven handle attributes than an individual expert. The Wool ComfortMeter provides a measure of the fibres that are protruding from the surface of the fabric that are responsible for the itchy sensation caused by some knitwear. The results from the instrument have been compared to the results from extensive wearer trials to provide an understanding of the relationship between the instrument value and the comfort perceptions of wearers. The results have shown a very clear relationship between the instrument and wearer trials

Identification of a QTL on chromosome 7AS for sodium exclusion in bread wheat

Tese de doutoramento em Engenharia Física (Instrumentação), apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraO número de ciclotrões com capacidade para acelerar protões até cerca de 20 MeV tem vindo a aumentar em todo o mundo. Apesar de o objectivo principal das instalaçõoes que contêm estas máquinas ser a produção de radionuclídeos para tomografia por emissão de positrões (PET, do inglês positron emission tomography), algumas dessas instalações estão equipadas com várias linhas de feixe que podem ser adaptadas para investigação científica. Por exemplo, radiobiologia, radiofisiolgia e outros estudos de dosimetria podem ser realizados utilizando uma destas linhas de feixe devidamente adaptada para o efeito. Neste trabalho, uma das linhas de feixe do ciclotrão PET da Universidade de Coimbra foi complementada e instrumentada por forma a possibilitar a irradiação de um arranjo experimental com um feixe de protões de elevada qualidade. Esta nova linha de feixe foi construída de raíz e sem causar qualquer interferência com as demais linhas do ciclotrão, dedicadas à produção de radionuclídeos. São apresentados resultados tanto experimentais como de simulação, estes últimos obtidos através dos pacotes de simulação SRIM/TRIM e Geant4, tendo como objectivo a medição do pico de Bragg depositado pelo feixe de protões do ciclotrão PET, com uma energia nominal de 18 MeV. Utilizando um bloco de plástico cintilador e uma câmara fotográfica com ligação à internet da marca D-link foi possível medir tanto o alcance como a largura do feixe de protões com uma resolução espacial inferior a 0,1 mm. Os alcances do feixe medidos após este passar pelo meio de um tubo de alumínio com vácuo com 40 cm de comprimento e um segundo tubo com 2,4 m de comprimento permitiram confirmar que a energia efectiva do feixe é de 18 MeV. Mediu-se também o pico de Bragg utilizando um alvo constituído por várias folhas de alumínio intercaladas com lâminas de polietileno. O sinal de corrente foi recolhido das várias folhas de alumínio através de amplificadores de transimpedância fabricados no âmbito desta tese. Verificou-se que o pico de Bragg assim medido é consistente com simulações realizadas utilizando o pacote SRIM/TRIM. Após a instalação da linha de feixe no perímetro exterior do ciclotrão, esta foi caracterizada, calibrada e validada. Para tal, o sinal induzido pela passagem do feixe por uma folha de alumínio com 20 μm de espessura é lido através do amplificador de transimpedância mencionado. Este sinal amplificado providencia informação de dose em tempo real através de um programa desenvolvido em C/C++. Para além da dose, as principais variáveis de monitorização que este programa providencia incluem a corrente do feixe, a carga integrada em conjunto com a taxa de dose. Deste modo a dose e a corrente integrada (carga total) entregue até um dado instante na montagem experimental pode ser controlada por meio de um obturador controlado por computador. Feixes de protões com correntes tão baixas como 10 pA podem deste modo ser aferidas. A folha de alumínio foi escolhida por ser resistente à radiação, possuir baixa densidade e baixa probabilidade de radioactividade induzida pelo feixe e, finalmente, por representar um custo negligenciável. Junta-se a estas vantagens o facto de o método potenciar o cálculo da dose entregue a um alvo durante uma irradiação, com uma perda mínima da energia do feixe de protões, e com dispersão igualmente mínima. Resultados experimentais e simulações com o Geant4 são apresentados que revelam a aplicação, pela primeira vez, de um feixe de 18 MeV proveniente de um ciclotrão para irradiação de uma região seleccionada de um alvo. Fazendo uso do sistema de dosimetria apresentado no parágrafo anterior foi possível irradiar de modo homogéneo uma região circular com 18 mm de diâmetro. Torna-se assim possível irradiar culturas celulares localizadas em placas multi-poços com um diâmetro por poço de 16 mm, como é usual em experiências de radiobiologia. Verificou-se que o controlo do campo magnético aplicado dentro do ciclotrão é crucial para se obter uma irradiação uniforme em todo o campo do alvo. Para tal, efetua-se antes de cada irradiação e com o obturador fechado, um varrimento à corrente que gera o campo magnético dentro do ciclotrão, medindo-se um perfil quase gaussiano e tomando-se o seu valor central para se obter uma irradiação homogénea. As taxas de dose no alvo (entre 500 mGy/s e 5 mGy/s) são obtidas através de um disco em rotação posicionado na trajectória do feixe. O disco, com 150 mm de raio e uma fenda de 0,5 mm na sua extermidade, permite reduzir a taxa de dose por um factor de 5×10−4. Finalmente, vários filmes do tipo Gafchromic EBT2 foram expostos a diferente valores de dose por forma a validar toda a instalação para irradiação de um alvo com feixes de protões. Para tal validação fez-se uso do sistema de dosimetria em filme 2D do Serviço de Radioterapia do Centro Hospitalar Universitário de Coimbra. A dose absoluta nos filmes irradiados com protões foi verificada neste sistema e apresentou uma precisão melhor que 2%.The number of cyclotrons capable of accelerating protons to about 20MeV is increasing throughout the world. Originally aiming at the production of positron emission tomography (PET) radionuclides, some of these facilities are equipped with several beamlines suitable for scientific research. Radiobiology, radiophysiology, and other dosimetric studies can be performed using these beamlines. In this work, a PET cyclotron was fitted with a long beam transport line to irradiate with a good quality proton beam experimental setups. The beamline was configured as a natural extension of one of the cyclotron beam ports, while keeping available the other beam ports for PET radionuclides production. Experimental results are reported, together with SRIM/TRIM and Geant4 simulations, which aim at measuring the Bragg peak of the 18 -MeV proton beam from the PET cyclotron. By using a piece of plastic scintillator and a D-link Ethernet-based camera, the proton beam range and width were measured with a spatial resolution of 0.1mm. The ranges of the proton beam in the plastic scintillator were used to assess its energy after trespassing one or two Havar R windows and either a 40-cm-long or a 2.4-m-long aluminum pipe. The initial energy of the proton beam from the PET cyclotron was found to be 18 MeV. Additionally, the Bragg peak of the protons from the PET cyclotron was assessed using a stacked target consisting of several aluminum foils interleaved with polyethylene sheets, readout by in-house made transimpedance electronics. The measured Bragg peak is consistent with simulations performed using the SRIM/TRIM simulation toolkit. An out-of-yoke irradiation setup using the accelerated proton beam coming from the PET cyclotron was developed, characterized, calibrated, and validated. A 20-μm-thick aluminum transmission foil is readout by in-house made transimpedance electronics, providing online dose information via a C/C++ program. xvii Overview The main monitoring variables include beam current, integrated charge together with dose rate. The beam monitor is able to readout and deliver these variables in real-time. Hence the dose and integrated current (total charge) delivered upto a given instant to an experimental setup may be controlled via a computercontrolled shutter that was installed in the beam path. Proton beam currents down to 10 pA can be assessed using the thin aluminum foil. The aluminum was chosen for this task because it is radiation hard, it has low density and low radiation activity, and finally because it is easily available at negligible cost. In addition, this method allows for calculating the dose delivered to a target during an irradiation with high efficiency, and with minimal proton energy loss and scattering. Experimental results and Geant4 simulations are reported, which aim at using for the first time the 18 -MeV proton beam from a PET cyclotron to irradiate a selected region of a target using the developed dosimetry system. By using this system, a homogeneous beam spot on target with a diameter of 18mm can be controlled. This allows controlled irradiation of cell cultures located in typical biological multi-well dishes with diameters of 16mm each. It was found that the control of the magnetic field applied inside the cyclotron plays a major role for achieving said homogeneity. For that, scanning the magnet current and measuring the corresponding dose rate reveals a quasi-Gaussian shaped curve that must be known before any irradiation procedure (the final shutter is closed during such measurements). The optimum magnet current is taken from the center of the Gaussian-shaped curve, hence producing a homogenous dose on target. The measured dose rate on target ranges from 500mGy/s down to 5mGy/s. This is achieved with a 150mm radius rotating disk with a slit of 0.5mm width, that decreases target dose rates by a factor of 5 × 10−4. Several Gafchromic R EBT2 films were exposed to different values of dose for validating the developed irradiation setup using the 2D film dosimetry system of the Department of Radiotherapy of Coimbra University Hospital Center. The absolute dose in the irradiated films were assessed with a precision better than 2%. It is planned, in the near future, to irradiate small animals, cell cultures, or other materials or samples

Impacts of Mid-Level Biofuel Content In Gasoline on SIDI Engine-Out and Tailpipe Particulate Matter Emissions

In this work, the influences of ethanol and iso-butanol blended with gasoline on engine-out and post three-way catalyst (TWC) particle size distribution and number concentration were studied using a General Motors (GM) 2.0L turbocharged spark ignition direct injection (SIDI) engine. The engine was operated using the production engine control unit (ECU) with a dynamometer controlling the engine speed and the accelerator pedal position controlling the engine load. A TSI Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle size distribution in the range from 5.6 to 560 nm with a sampling rate of 1 Hz. U.S. federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuel (BU12) were tested. Measurements were conducted at 10 selected steady-state engine operation conditions. Bi-modal particle size distributions were observed for all operating conditions with peak values at particle sizes of 10 nm and 70 nm. Idle and low-speed / low-load conditions emitted higher total particle numbers than other operating conditions. At idle, the engine-out particulate matter (PM) emissions were dominated by nucleation mode particles, and the production TWC reduced these nucleation mode particles by more than 50%, while leaving the accumulation mode particle distribution unchanged. At an engine load higher than 6 bar net mean effective pressure (NMEP), accumulation mode particles dominated the engine-out particle emissions, and the TWC had little effect. Compared to the baseline gasoline (E0), E10 does not significantly change PM emissions, while E20 and BU12 both reduce PM emissions under the conditions studied. Iso-butanol was observed to impact PM emissions more than ethanol, with up to 50% reductions at some conditions. In this paper, issues related to PM measurement using the FMPS are also discussed. While some uncertainties are due to engine variation, the FMPS must be carefully maintained in order to achieve repeatable measurement results