2,523 research outputs found
Evaluation of advanced combustion concepts for dry NO sub x suppression with coal-derived, gaseous fuels
The emissions performance of a rich lean combustor (developed for liquid fuels) was determined for combustion of simulated coal gases ranging in heating value from 167 to 244 Btu/scf (7.0 to 10.3 MJ/NCM). The 244 Btu/scf gas is typical of the product gas from an oxygen blown gasifier, while the 167 Btu/scf gas is similar to that from an air blown gasifier. NOx performance of the rich lean combustor did not meet program goals with the 244 Btu/scf gas because of high thermal NOx, similar to levels expected from conventional lean burning combustors. The NOx emissions are attributed to inadequate fuel air mixing in the rich stage resulting from the design of the large central fuel nozzle delivering 71% of the total gas flow. NOx yield from ammonia injected into the fuel gas decreased rapidly with increasing ammonia level, and is projected to be less than 10% at NH3 levels of 0.5% or higher. NOx generation from NH3 is significant at ammonia concentrations significantly less than 0.5%. These levels may occur depending on fuel gas cleanup system design. CO emissions, combustion efficiency, smoke and other operational performance parameters were satisfactory. A test was completed with a catalytic combustor concept with petroleum distillate fuel. Reactor stage NOx emissions were low (1.4g NOx/kg fuel). CO emissions and combustion efficiency were satisfactory. Airflow split instabilities occurred which eventually led to test termination
Low NO sub x heavy fuel combustor concept program phase 1A gas tests
The emissions performance of a rich lean combustor (developed for liquid fuels) for combustion of simulated coal gases ranging in heating value from 167 to 244 Btu/scf were assessed. The 244 Btu/scf gas is typical of the product gas from an oxygen blown gasifier, while the 167 Btu/scf gas is similar to that from an air blown gasifier. Although meeting NOx goals for the 167 Btu/scf gas, NOx performance of the rich lean combustor did not meet program goals with the 244 Btu/scf gas because of high thermal NOx, similar to levels expected from conventional lean burning combustors. The NOx emissions are attributed to inadequate fuel air mixing in the rich stage resulting from the design of the large central fuel nozzle delivering 71% of the total gas flow. NOx generation from NH3 was significant at ammonia concentrations significantly less tha 0.5%. These levels occur depending on fuel gas cleanup system design, However, NOx yield from ammonia injected into the fuel gas decreased rapidly with increasing ammonia level, and is projected to be less than 10% at NH3 levels of 0.5% or higher
Real-world comparison of probe vehicle emissions and fuel consumption using diesel and 5 % biodiesel (B5) blend.
An instrumented EURO I Ford Mondeo was used to perform a real-world comparison of vehicle exhaust (carbon dioxide, carbon monoxide, hydrocarbons and oxides of nitrogen) emissions and fuel consumption for diesel and 5% biodiesel in diesel blend (B5) fuels. Data were collected on multiple replicates of three standardised on-road journeys: (1) A simple urban route; (2) A combined urban/inter-urban route; and, (3) An urban route subject to significant traffic management. At the total journey measurement level, data collected here indicate that replacing diesel with a B5 substitute could result in significant increases in both NOx emissions (8-13%) and fuel consumption (7-8%). However, statistical analysis of probe vehicle data demonstrated the limitations of comparisons based on such total journey measurements, i.e., methods analogous to those used in conventional dynamometer/drive cycle fuel comparison studies. Here, methods based on the comparison of speed/acceleration emissions and fuel consumption maps are presented. Significant variations across the speed/acceleration surface indicated that direct emission and fuel consumption impacts were highly dependent on the journey/drive cycle employed. The emission and fuel consumption maps were used both as descriptive tools to characterise impacts and predictive tools to estimate journey-specific emission and fuel consumption effects
Conductivity in Jurkat cell suspension after ultrashort electric pulsing
Ultrashort electric pulses applied to similar cell lines such as Jurkat and HL-60 cells can produce markedly different results , which have been documented extensively over the last few years. We now report changes in electrical conductivity of Jurkat cells subjected to traditional electroporation pulses (50 ms pulse length) and ultrashort pulses (10 ns pulse length) using time domain dielectric spectroscopy (TDS). A single 10 ns, 150 kV/cm pulse did not noticeably alter suspension conductivity while a 50 ms, 2.12 kV/cm pulse with the same energy caused an appreciable conductivity rise. These results support the hypothesis that electroporation pulses primarily interact with the cell membrane and cause conductivity rises due to ion transport from the cell to the external media, while pulses with nanosecond duration primarily interact with the membranes of intracellular organelles. However, multiple ultrashort pulses have a cumulative effect on the plasma membrane, with five pulses causing a gradual rise in conductivity up to ten minutes post-pulsing
Purification and Characterization of a cAMP- and Ca2+-Calmodulin-Independent Glycogen Synthase Kinase from Porcine Renal Cortex
We recently reported the partial purification of a cAMP-independent and Ca2+-calmodulin-independent glycogen synthase kinase from porcine renal cortex (Schlender, K. K., Beebe, S. J., and Reimann, E. M. (1981) Cold Spring Harbor Conf. Cell Proliferation, 389-400). Subsequent purification indicated that the enzyme preparation consisted of at least three forms of glycogen synthase kinase which could be resolved by ATP gradient elution from aminoethylphosphate-agarose (AEP-agarose). The predominant form of glycogen synthase kinase, which eluted from AEP-agarose between 2 and 6 mM ATP, was purified approximately 800-fold and is designated GSK-A1. It had a molecular weight of 45,000-50,000 as determined by gel filtration and sucrose density gradient centrifugation. It catalyzed the transfer of 1 mol of 32P/mol of synthase subunit into a low molecular weight (10,000) CNBr peptide which was tentatively identified as Ser-7 (site 2) by high performance liquid chromatography. This phosphorylation decreased the activity ratio (activity in the absence of glucose-6-P divided by activity in the presence of 7.2 mM glucose-6-P) from 0.95 to about 0.55. GSK-A1 appeared to be specific for and had low s0.5 values for both substrates, ATP (13 µM) and glycogen synthase (0.3-0.4 µM). The enzyme could not use GTP as the phosphate donor. GSK-A1 was not affected by the protein kinase inhibitor, cAMP, cGMP, Ca2+-calmodulin, EGTA, or trifluoperazine and had a broad pH optimum (pH 7.0-8.5). A second form, GSK-A2, was eluted from AEP-agarose between 7 and 9 mM ATP. GSK-A2 could transfer a 2nd mol of 32P/mol of synthase subunit and decreased the activity ratio to 0.30. The interrelation among these multiple forms is not clear, but the data suggest that multiple kinases are required to form the highly inactivated glycogen synthase in renal tissues
Framing Information Security Budget Requests to Influence Investment Decisions
Researchers studying the economics of information security have traditionally focused on the use of rational choice decision models for evaluating investment alternatives. Security investment decisions involve risk, and several researchers have noted that risk-related decisions often violate the fundamental principles of rational choice decision models. This study tests the prevailing presumption in published research that information security investment decisions are made in an entirely rational manner. We empirically validated our hypothesis that information security investment decision makers in fact exhibit preference reversals when faced with competing budget alternatives involving risk. Specifically, we observed the framing effect under prospect theory, which suggests that individuals exhibit unique risk attitudes when evaluating gain-related and loss-related risk decisions. Accordingly, we argue that existing, widely accepted rational choice and economic models for information security investments need to be supplemented with risk perception measurement and account for individual level decision biases
Advanced Onboard Spacecraft Guidance and Navigation Console
This proposal defines an advanced onboard navigation interface and trajectory design tool for future astronauts. As the space industry expands and becomes more commercialized, future spaceflight will include long-duration exploration to more distant destinations. Mission tasks, such as rendezvous, docking, descent, landing, and in-space trajectory planning will become commonplace. Presently, many of these tasks are performed with the assistance of ground-based mission control. The onboard crew typically has limited control of vehicle guidance and navigation. This is in stark contrast with the more mature commercial and private aircraft industry, for which guidance, navigation and control are operated primarily by the crew. As the space industry continues to expand with more and more space vehicles, it will become necessary and desirable for the crew to have independent onboard guidance, navigation and control capability. It will not be possible nor efficient to have ground-control operations of every space vehicle, particularly those that are distant from Earth. Just as the pilot operates a suite of instruments and controls on a conventional aircraft, new concepts for spacecraft crew interfaces will be needed for future space pilots.
As such, this research proposes the conception and design of an onboard spacecraft pilot interface called the “Spaceflight Console.” The purpose is to provide the crew full autonomy for spacecraft navigation and guidance via touch-controls and holographic visual displays. The objective is to design an intuitive interface for onboard trajectory planning and a wide range of mission tasks that will become more commonplace in the future, such as interplanetary departure, trajectory corrections, orbital insertion, rendezvous, station keeping, landing site selection and targeting, and so on.
The proposed Spaceflight Console will be built and demonstrated using a virtual-reality (VR) engineering-design platform designed by the ASTRO Lab at Texas A&M, called SpaceCRAFT. Using SpaceCRAFT crew interfaces can be designed, evaluated in the context of a mission environment in VR, and revised easily. Control panels for crew selections or data entry will be coupled with 3D visual displays that enable crew situational awareness in an orbital or interplanetary context. Similar to an aircraft cockpit and the usual suite of flight instruments, the Spaceflight Console presents intuitive information to the crew while internally performing complex computations to support the mission tasks. In effect, the Spaceflight Console aims to translate many complex ground-control capabilities into a fully onboard system with a simple and intuitive interface that operates from the pilot’s perspective
Nanosecond electric pulses penetrate the nucleus and enhance speckle formation
Nanosecond electric pulses generate nanopores in the interior membranes of cells and modulate cellular functions. Here, we used confocal microscopy and flow cytometry to observe Smith antigen antibody (Y12) binding to nuclear speckles, known as small nuclear ribonucleoprotein particles (snRNPs) or intrachromatin granule clusters (IGCs), in Jurkat cells following one or five 10 ns, 150 kV/cm pulses. Using confocal microscopy and flow cytometry, we observed changes in nuclear speckle labeling that suggested a disruption of pre-messenger RNA splicing mechanisms. Pulse exposure increased the nuclear speckled substructures by 2.5-fold above basal levels while the propidium iodide (PI) uptake in pulsed cells was unchanged. The resulting nuclear speckle changes were also cell cycle dependent. These findings suggest that 10 ns pulses directly influenced nuclear processes, such as the changes in the nuclear RNA–protein complexes
Pilgrimage and textual culture
Pilgrimage formed a central motif of medieval culture and shaped a defining aesthetic of early literature. Despite this centrality, research remains in a preliminary state for many of the actual texts, manuscripts, and books connected to pilgrimage and how they contributed to the exchange and translation of knowledge and ideas. This special issue considers issues of reading and writing before, during, and after medieval pilgrimages, as well as the methodological and historical issues at stake for both pilgrim writers and modern scholars. In particular, the articles address the vexed issue of where—and how much—reading and writing took place around historically attested pilgrimages. By employing insights from literature, history, bibliography, geography, and anthropology, this collection aims not only to understand the past, but also to examine how current biases might affect interpretation of that past. From this multidisciplinary perspective, deeper insight is offered into how pilgrims’ libraries shaped not only pilgrimage, but medieval culture in general
An Empirical Examination of an Agile Contingent Project/Method Fit Model
While research has demonstrated positive productivity and quality gains from using agile software development methods (SDMs), some experts argue that no single SDM suits every project context. We lack empirical evidence about the project contextual factors that influence when one should use these methods. Research suggests several factors to explain agile method appropriateness; however, generalizable empirical evidence supporting these suggestions is weak. To address this need, we used contingency theory and the information processing model to develop the agile contingent project/method fit model. Subsequently, we used the model to analyze the influence of project contextual factors and agile practices on software development professionals’ perceptions regarding agile SDM appropriateness. We tested the model using survey data collected from 122 systems development professionals who provided information regarding: 1) contextual factors surrounding a recent agile development project, 2) agile practices applied during the course of that project, and 3) perceptions regarding the relative fit (appropriateness) of the agile method used. Linear regression identified several significant relationships between project contextual factors, agile practices, and respondents’ relative fit perceptions
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