4 resultados para equivalence
em Bucknell University Digital Commons - Pensilvania - USA
Resumo:
Pictorial representations of three-dimensional objects are often used to investigate animal cognitive abilities; however, investigators rarely evaluate whether the animals conceptualize the two-dimensional image as the object it is intended to represent. We tested for picture recognition in lion-tailed macaques by presenting five monkeys with digitized images of familiar foods on a touch screen. Monkeys viewed images of two different foods and learned that they would receive a piece of the one they touched first. After demonstrating that they would reliably select images of their preferred foods on one set of foods, animals were transferred to images of a second set of familiar foods. We assumed that if the monkeys recognized the images, they would spontaneously select images of their preferred foods on the second set of foods. Three monkeys selected images of their preferred foods significantly more often than chance on their first transfer session. In an additional test of the monkeys' picture recognition abilities, animals were presented with pairs of food images containing a medium-preference food paired with either a high-preference food or a low-preference food. The same three monkeys selected the medium-preference foods significantly more often when they were paired with low-preference foods and significantly less often when those same foods were paired with high-preference foods. Our novel design provided convincing evidence that macaques recognized the content of two-dimensional images on a touch screen. Results also suggested that the animals understood the connection between the two-dimensional images and the three-dimensional objects they represented.
Resumo:
An atmospheric combustion apparatus was designed through several iterations for Bucknell University's combustion laboratory. The final design required extensive fine-tuning of the fuel and air systems and repeated tests to arrive at a satisfactory procedure to transfer from gaseous to liquid fuel operation. Measurement of exhaust emissions were obtained under tests of gaseous methane and liquid heptane were operation in order to validate the functionality of the combustion apparatus, the fuel transition procedure, and emissions analyzer systems. The emission concentrations of CO, CO2, NOx, 02, S02, and unburned hydrocarbons from a multianalyzer and HFID analyzer were obtained for a range of equivalence ratios. The results verify the potential for future alternative fuel tests and illuminate necessary alterations for further liquid fuel studies.
Resumo:
The atom transfer radical polymerization (ATRP) of styrene (St) was conducted in the presence of varying equivalence (eq) of hexafluorobenzene (HFB) and octafluorotoluene (OFT) to probe the effects of pi-pi stacking on the rate of the polymerization and on the tacticity of the resulting polystyrene (PSt). The extent of the pi-pi stacking interaction between HFB/OFT and the terminal polystyrenic phenyl group was also investigated as a function of solvent, both non-aromatic solvents (THF and hexanes) and aromatic solvents (benzene and toluene). In all cases the presence of HFB or OFT resulted in a decrease in monomer conversion indicating a reduction in the rate of the polymerization with greater retardation of the rate with increase eq of HFB or OFT (0.5 eq to 1 eq HFB/OFT compared to St). Additionally, when aromatic solvents were used instead of non-aromatic solvents the effect of the HFB/OFT on the rate was minimized, consistent with the aromatic solvent competitively interacting with the HFB/OFT. The effects of temperature and ligand strength on the ATRP of St in the presence of HFB were also probed. It was found that when using N,N,N’,N’,N’’-pentamethyldiethylenetriamine (PMDETA) as the ligand the effects of HFB at 38o were the same as at 86oC. When tris[2-(dimethylamino)ethyl]-amine (Me6TREN) was used as the ligand at 38o there was a decrease in monomer conversion similar to the analogous PMDETA reaction. When the polymerization was conducted at 86oC there was no effect on the monomer conversion with HFB present compared to when HFB was absent. To investigate the pi-pi stacking effect even further, the reverse pi-pi stacking system was observed by conducting the ATRP of pentafluorostyrene (PFSt) in the presence of varying eq of benzene and toluene, which in both cases resulted in an increase in monomer conversion compared to when benzene or toluene were absent; in summary the rate of the ATRP of PFSt increases when benzene or toluene waas present in the reaction. The pi-pi stacking interaction between the HFB/OFT and the dormant alkyl bromide of the polymer chain was verified by 1H-NMR with 1-bromoethylbenzene as the alkyl bromide. Also verified by 1H-NMR was the interaction between HFB/OFT and St and the interaction between PFSt and benzene. In all 1H-NMR spectra a perturbation in the aromatic and/or vinyl peaks was observed when the pi-pi stacking agent was present compared to when it was absent. The tacticity of the PSt formed in the presence of 1 eq of HFB was compared to the PSt formed in the absence of HFB by observing the C1 signal in their 13C-NMR spectra, but no change in shape or chemical shift of the signal was observed indicating that there was no change in tacticity.
Resumo:
Utilization of biogas can provide a source of renewable energy in both heat and power generation. Combustion of biogas in land-based gas turbines for power generation is a promising approach to reducing greenhouse gases and US dependence on foreign-source fossil fuels. Biogas is a byproduct from the decomposition of organic matter and consists primarily of CH4 and large amounts of CO2. The focus of this research was to design a combustion device and investigate the effects of increasing levels of CO2 addition to the combustion of pure CH4 with air. Using an atmospheric-pressure, swirl-stabilized dump combustor, emissions data and flame stability limitations were measured and analyzed. In particular, CO2, CO, and NOx emissions were the main focus of the combustion products. Additionally, the occurrence of lean blowout and combustion pressure oscillations, which impose significant limitations in operation ranges for actual gas turbines, was observed. Preliminary kinetic and equilibrium modeling was performed using Cantera and CEA for the CH4/CO2/Air combustion systems to analyze the effect of CO2 upon adiabatic flame temperature and emission levels. The numerical and experimental results show similar dependence of emissions on equivalence ratio, CO2 addition, inlet air temperature, and combustor residence time. (C) 2014 Elsevier Ltd. All rights reserved.