An investigation of conducted and radiated emissions from a hollow-cathode plasma contactor

An investigation conducted on the electrical interference induced by the operation of a hollow-cathode plasma contractor in a ground-based facility is described. The types of electrical interference, or noise, which are important to Space Station Freedom designers are classified as either conducted or radiated emissions. The procedures required to perform conducted and radiated emission measurements on a plasma contactor are examined. The experimental data obtained are typically examined in the frequency domain (i.e. amplitudes of the noise fluctuations versus frequency). Results presented indicate the conducted emissions, which are the current fluctuations from the contactor into the space station wiring, are affected by operating parameters such as expellant flow rate and discharge current. The radiated emissions, which are the electromagnetic waves induced and emitted by the contactor, appear to be influenced by the contactor emission current. Other experimental results suggest possible sources which are responsible for the observed noise. For example, the influence of the plasma environment downstream from the contactor on noise emission levels is described. In addition, a brief discussion is given on the correlation between conducted and radiated emissions and the mechanisms through which both are influenced by the plasma downstream of the contactor

Sufficient exercise for Australians living with dementia in residential aged care facilities is lacking: An exploration of policy incoherence

Along with cognitive decline, dementia is characterised by changes in emotional control, social behaviour and physical performance.1 Individuals living with dementia often require assistance with their activities of daily living as dementia progresses.2 Requirements for higher levels of care result in more individuals with dementia living in residential aged care facilities (RACFs); up to 52% of all individuals living in RACFs have a diagnosis of dementia

Structural change of fluid catalytic cracking catalysts study incorporate with coke characterization formed in heavy oil volatilization/decomposition

Porous structure change of catalyst and coke formation from feedstock on fluid catalytic cracking (FCC) catalyst have studied by a more comprehensive set of analyses, include 2D, 3D analyses incorporate with carbon/coke characterization teniques. Carbon/coke formed from a heavy oil volatilization/decomposition with different oil-to-FCC catalyst ratio (1:3, 1:2, 1:1, 2:1 and 3:1) to simulate the aging of FCC catalyst in a continuous oil refinery. Carbon/coke was formed for all used FCC catalyst samples that is generally increases with the increase of oil-to-FCC catalyst ratio. Coke formation has been correlated with the porosity change of the FCC catalyst, that more carbon/coke formed on the FCC catalyst due to the increment of oil-to-FCC catalyst ratio leads to the decrease of total pore volume and surface area. Zeolite is evenly distributed from the FCC catalyst particle centre to the exterior for all pristine and used FCC catalyst particles. The interior porous structure of single FCC catalyst particle is not affected by the coking. However, the exterior porous structure is completely disappear for all used FCC catalyst, that could cause by porous frame collapse and the coking clog the surface pores. The more comprehensive study of the structural change incorporate with the carbon/coke characterisation, which helps to understand the progressive degredation of FCC catalyst caused by porous structure change more in depth. Figure 1 is an example of 3 D tomogram and the radial distribution profiles of pristine FCC catalyst. Please click Additional Files below to see the full abstract

Plasma contactor research - 1991

A report describing the operating principles of hollow-cathode-based plasma contactors emitting or collecting electrons from an ambient plasma is summarized. Preliminary experiments conducted to determine the noise generated by these plasma contactors in the emission-current return line and in the plasma near it are described. These noise data are measured as current fluctuations in the return line and to the Langmuir probe and then analyzed using a fast Fourier transform technique. The spectral compositions of the data are characterized using power spectral density plots which are examined to identify possible noise source(s) and production mechanism(s). The precautions taken in the construction and calibration of the instrumentation to assure adequate frequency response are described. Experimental results show that line-current noise levels are typically 2 percent of the electron current being emitted or collected. However, noise levels increase to as much as 20 percent of the electron current at a few electron-collection operating conditions. The frequencies associated with most of the noise were harmonics of the 60 Hz input to system power supplies. Plasma noise had characteristics similar in magnitude and frequency to those for the return-line noise, but they contained additional features at frequencies considered to be related to ion-acoustic instabilities. Also discussed is a new probe positioning system built to facilitate future plasma-contractor research

Can the United States Afford a “No-Fault” System of Compensation for Medical Injury?

One of the key issues separating US critics of a no-fault alternative to the tort system for compensating victims of medical injury from supporters is its anticipated cost. Results from a study are presented that estimate the costs of a no-fault system, one that is similar to the system now in operation in Sweden, within the context of the US health care system

Treponema denticola TroR is a manganese- and iron-dependent transcriptional repressor

Treponema denticola harbours a genetic locus with significant homology to most of the previously characterized Treponema pallidum tro operon. Within this locus are five genes ( troABCDR ) encoding for the components of an ATP-binding cassette cation-transport system ( troABCD ) and a DtxR-like transcriptional regulator ( troR ). In addition, a σ 70 -like promoter and an 18 bp region of dyad symmetry were identified upstream of the troA start codon. This putative operator sequence demonstrated similarity to the T. pallidum TroR (TroR Tp ) binding sequence; however, the position of this motif with respect to the predicted tro promoters differed. Interestingly, unlike the T. pallidum orthologue, T. denticola TroR (TroR Td ) possesses a C-terminal Src homology 3-like domain commonly associated with DtxR family members. In the present study, we show that TroR Td is a manganese- and iron-dependent transcriptional repressor using Escherichia coli reporter constructs and in T. denticola . In addition, we demonstrate that although TroR Td possessing various C-terminal deletions maintain metal-sensing capacities, these truncated proteins exhibit reduced repressor activities in comparison with full-length TroR Td . Based upon these findings, we propose that TroR Td represents a novel member of the DtxR family of transcriptional regulators and is likely to play an important role in regulating both manganese and iron homeostases in this spirochaete.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72265/1/j.1365-2958.2008.06418.x.pd

Solutions of Higher Dimensional Gauss-Bonnet FRW Cosmology

We examine the effect on cosmological evolution of adding a Gauss-Bonnet term to the standard Einstein-Hilbert action for a (1 + 3)+ d dimensional Friedman-Robertson-Walker (FRW) metric. By assuming that the additional dimensions compactify as a power law as the usual 3 spatial dimensions expand, we solve the resulting dynamical equations and find that the solution may be of either de Sitter or Kasner form depending upon whether the Gauss-Bonnet term or the Einstein term dominates.Comment: 10 pages, references added/corrected, accepted for publication in General Relativity and Gravitatio

Analysis of the Two-Level NO PLIF Model for Low-Temperature High-Speed Flow Applications

The current work compares experimentally obtained nitric oxide (NO) laser-induced fluorescence (LIF) spectra with the equivalent spectra obtained analytically. The experimental spectra are computed from captured images of fluorescence in a gas cell and from a laser sheet passing through the fuel-air mixing flowfield produced by a high-speed fuel injector. The fuel injector is a slender strut that is currently being studied as a part of the Enhanced Injection and Mixing Project (EIMP) at the NASA Langley Research Center. This injector is placed downstream of a Mach 6 facility nozzle, which simulates the high Mach number airflow at the entrance of a scramjet combustor, and injects helium, which is used as an inert substitute for hydrogen fuel. Experimental planar (P) LIF is obtained by using a UV laser to excite fluorescence from the NO molecules that are present in either a gas cell or the facility air used for the EIMP experiments. The experimental data are obtained for several segments of the NO fluorescence spectrum. The selected segments encompass LIF lines with rotational quantum numbers appropriate for low-to-moderate temperature flows similar to those corresponding to the nominal experimental flow conditions. The experimental LIF spectra are then evaluated from the data and compared with those obtained from the theoretical models. The theoretical spectra are obtained from LIFBASE and LINUS software, and from a simplified version of the two-level fluorescence model. The equivalent analytic PLIF images are also obtained by applying only the simplified model to the results of the Reynolds-averaged simulations (RAS) of the mixing flowfield. Good agreement between the experimental and theoretical results provides increased confidence in both the simplified LIF modeling and CFD simulations for further investigations of high-speed injector performance using this approach

On the origin and application of the Bruggeman Correlation for analysing transport phenomena in electrochemical systems

The widely used Bruggeman equations correlate tortuosity factors of porous media with their porosity. Finding diverse application from optics to bubble formation, it received considerable attention in fuel cell and battery research, recently. The ability to estimate tortuous mass transport resistance based on porosity alone is attractive, because direct access to the tortuosity factors is notoriously difficult. The correlation, however, has limitations, which are not widely appreciated owing to the limited accessibility of the original manuscript. We retrace Bruggemans derivation, together with its initial assumptions, and comment on validity and limitations apparent from the original work to offer some guidance on its use.<br/

Small-Area Estimation for the USDA Forest Service, National Woodland Owner Survey: Creating a Fine-Scale Land Cover and Ownership Layer to Support County-Level Population Estimates

Small area estimation is a powerful modeling technique in which ancillary data can be utilized to “borrow” additional information, effectively increasing sample sizes in small spatial, temporal, or categorical domains. Though more commonly applied to biophysical variables within the study of forest inventory analyses, small area estimation can also be implemented in the context of understanding social values, behaviors, and trends among types of forest landowners within small domains. Here, we demonstrate a method for deriving a continuous fine-scale land cover and ownership layer for the state of Delaware, United States, and an application of that ancillary layer to facilitate small-area estimation of several variables from the USDA Forest Service’s National Woodland Owner Survey. Utilizing a proprietary parcel layer alongside the National Land Cover Database, we constructed a continuous layer with 10-meter resolution depicting land cover and land ownership classes. We found that the National Woodland Owner Survey state-level estimations of total acreage and total ownerships by ownership class were generally within one standard error of the population values calculated from the raster layer, which supported the direct calculation of several population-level summary variables at the county levels. Subsequently, we compare design-based and model-based methods of predicting commercial harvesting by family forest ownerships in Delaware in which forest ownership acreage, taken from the parcel map, was utilized to inform the model-based approach. Results show general agreement between the two modes, indicating that a small area estimation approach can be utilized successfully in this context and shows promise for other variables, especially if additional variables, e.g., United States Census Bureau data, are also incorporated