Air bearing Patent

Air bearings for near frictionless transfer of loads from one body to anothe

Chemical kinetic modeling of benzene and toluene oxidation behind shock waves

The oxidation of stoichiometric mixtures of benzene and toluene behind incident shock waves was studied for a temperature range from 1700 to 2800 K and a pressure range from 1.1 to 1.7 atm. The concentration of CO and CO2 produced were measured as well as the product of the oxygen atom and carbon monoxide concentrations. Comparisons between the benzene experimental data and results calculated by use of a reaction mechanism published in the open literature were carried out. With some additional reactions and changes in rate constants to reflect the pressure-temperature range of the experimental data, a good agreement was achieved between computed and experimental results. A reaction mechanism was developed for toluene oxidation based on analogous rate steps from the benzene mechanism. Measurements of NOx levels in an actual flame device, a jet-stirred combustor, were reproduced successfully by use of the reaction mechanism developed from the shock-tube experiments on toluene. These experimental measurements of NOx levels were reproduced from a computer simulation of a jet-stirred combustor

Analysis of Volatile Organic Compounds in the Apollo Next Generation Sample Analysis (ANGSA) 73002 Core Sample

Understanding the organic content of lunar regolith was an early priority upon the return of Apollo samples, with amino acids being of special interest because of their importance to life on Earth and their astrobiological relevance. Many initial studies focused on the detection of amino acids in these samples and attempts to determine the origin of those compounds. Although no consensus on the origin of the amino acids was reached in those early studies, more recent work determined that the detected amino acids originated from both terrestrial contamination and meteoritic or cometary in fall to the lunar surface. A majority of the amino acids in the Apollo samples studied originated from precursor molecules, either indigenous to the lunar samples or contaminants, that reacted during the water extraction and acid hydrolysis process for analysis in the laboratory, but the identities of the amino acid precursors still remain poorly understood. Such precursors could include hydrogen cyanide (HCN) and other volatile organic compounds such as amines, carboxylic acids, or aldehydes and ketones. The identities of these compounds, as well as the effects of years of curation on their abundances in lunar regolith samples stored at ambient temperature under nitrogen gas purge, are not clear. The specially curated samples available through the Apollo Next Generation Sample Analysis (ANGSA) program provide a unique opportunity to use state-of- the-art analytical techniques to examine previously unstudied lunar materials. The ANGSA samples include three types of samples: 1) samples stored frozen since <1 month after Earth arrival; 2) samples stored under helium; and 3) a double drive tube collected by Apollo 17 astronauts, with the bottom portion of the drive tube sealed under vacuum on the Moon and never opened. In contrast to the typically curated Apollo samples that have been kept for decades at room temperature under flowing nitrogen purge that may have significantly reduced the abundance of volatiles, the vacuum-sealed and frozen samples may have enhanced preservation of these volatiles. Our initial investigation examines amino acids and their potential volatile precursors, including hydrogen cyanide (HCN), aldehydes, ketones, amines, and mono-carboxylic acids, in a sample from the top portion of the Apollo 17 double drive tube. These results will aid in understanding the lunar abundances of these molecules and will also be compared to future analyses of other drive tube and frozen ANGSA samples

An office building used as a federal test bed for energy-efficient roofs

The energy savings benefits of re-covering the roof of an existing federal office building with a sprayed polyurethane foam system are documented. The building is a 12,880 ft{sup 2} (1,197 m{sup 2}), 1 story, masonry structure located at the Oak Ridge National Laboratory (ORNL), Oak Ridge, TN. Prior to re-covering, the roof had a thin fiberglass insulation layer, which had become partially soaked because of water leakage through the failed built-up roof membrane. The average R-value for this roof measured at 2 hr{center_dot}ft{sup 2}{center_dot}{degrees}F/Btu (0.3 m{sup 2} {center_dot}K/W). After re-covering the roof, it measured at 13 hr{center_dot}ft{sup 2}{degrees}F/Btu (2.3 m{sup 2}{center_dot}K/W). The building itself is being used as a test bed to document the benefits of a number of energy efficiency improvements. As such, it was instrumented to measure the half-hourly energy consumption of the whole building and of the individual rooftop air conditioners, the roof heat fluxes and the interior air and roof temperatures. These data were used to evaluate the energy effectiveness of the roof re-covering action. The energy savings analysis was done using the DOE-2.lE building simulation program, which was calibrated to match the measured data. The roof re-covering led to around 10% cooling energy savings and around 50% heating energy savings. The resulting energy cost reductions alone are not sufficient to justify re-covered roofs for buildings having high internal loads, such as the building investigated here. However the energy savings do contribute significantly to the measure`s Savings-to-Investment Ratio (SIR)

Impact evaluation of the energy retrofits installed in the Margolis high-rise apartment building, Chelsea housing authority

As part of a joint demonstration effort involving HUD, DOE, a local public housing authority and Boston Edison, an evaluation of energy and demand saving retrofits was conducted for a tall, residential, low-income building located in Boston. The thirteen story building underwent window, lighting, and heating system control renovations in December, 1992. The success of these retrofits was determined using monthly and hourly whole-building consumption data along with a calibrated DOE-2.1D energy simulation model. According to the model developed, post-retrofit conditions showed reductions in annual energy consumption of 325 MWh and in peak demand of 100 kW. These savings resulted in an annual energy cost savings of $28,000. Over 90$2,500

Information mobility in complex networks

The concept of information mobility in complex networks is introduced on the basis of a stochastic process taking place in the network. The transition matrix for this process represents the probability that the information arising at a given node is transferred to a target one. We use the fractional powers of this transition matrix to investigate the stochastic process at fractional time intervals. The mobility coefficient is then introduced on the basis of the trace of these fractional powers of the stochastic matrix. The fractional time at which a network diffuses 50% of the information contained in its nodes (1/ k50 ) is also introduced. We then show that the scale-free random networks display better spread of information than the non scale-free ones. We study 38 real-world networks and analyze their performance in spreading information from their nodes. We find that some real-world networks perform even better than the scale-free networks with the same average degree and we point out some of the structural parameters that make this possible

Distribution and Origin of Amino Acids in Lunar Regolith Samples

The existence of organic compounds on the lunar surface has been a question of interest from the Apollo era to the present. Investigations of amino acids immediately after collection of lunar samples yielded inconclusive identifications, in part due to analytical limitations including insensitivity to certain compounds, an inability to separate enantiomers, and lack of compound-specific isotopic measurements. It was not possible to determine if the detected amino acids were indigenous to the lunar samples or the result of terrestrial contamination. Recently, we presented initial data from the analysis of amino acid abundances in 12 lunar regolith samples and discussed those results in the context of four potential amino acid sources [5]. Here, we expand on our previous work, focusing on amino acid abundances and distributions in seven regolith samples and presenting the first compound-specific carbon isotopic ratios measured for amino acids in a lunar sample

Visual 3-D SLAM from UAVs

The aim of the paper is to present, test and discuss the implementation of Visual SLAM techniques to images taken from Unmanned Aerial Vehicles (UAVs) outdoors, in partially structured environments. Every issue of the whole process is discussed in order to obtain more accurate localization and mapping from UAVs flights. Firstly, the issues related to the visual features of objects in the scene, their distance to the UAV, and the related image acquisition system and their calibration are evaluated for improving the whole process. Other important, considered issues are related to the image processing techniques, such as interest point detection, the matching procedure and the scaling factor. The whole system has been tested using the COLIBRI mini UAV in partially structured environments. The results that have been obtained for localization, tested against the GPS information of the flights, show that Visual SLAM delivers reliable localization and mapping that makes it suitable for some outdoors applications when flying UAVs

Communicability in complex networks

Many topological and dynamical properties of complex networks are defined by assuming that most of the transport on the network flows along the shortest paths. However, there are different scenarios in which non-shortest paths are used to reach the network destination. Thus the consideration of the shortest paths only does not account for the global communicability of a complex network. Here we propose a new measure of the communicability of a complex network, which is a broad generalization of the concept of the shortest path. According to the new measure, most of real-world networks display the largest communicability between the most connected (popular) nodes of the network (assortative communicability). There are also several networks with the disassortative communicability, where the most "popular" nodes communicate very poorly to each other. Using this information we classify a diverse set of real-world complex systems into a small number of universality classes based on their structure-dynamic correlation. In addition, the new communicability measure is able to distinguish finer structures of networks, such as communities into which a network is divided. A community is unambiguously defined here as a set of nodes displaying larger communicability among them than to the rest of nodes in the network.Comment: 20 pages, 5 figure

Impact of recurrent Clostridium difficile infection: hospitalization and patient quality of life

Objectives: Data quantifying outcomes of recurrent Clostridium difficile infection (rCDI) are lacking. We sought to determine the UK hospital resource use and health-related quality of life (HrQoL) associated with rCDI hospitalisations. Patients and methods: A non-interventional study in 6 UK acute hospitals collected retrospective clinical and resource use data from medical records of 64 adults hospitalised for rCDI and 64 matched inpatient controls with a first episode only (f)CDI. Patients were observed from the index event (date rCDI/fCDI confirmed) for 28-days (or death, if sooner); UK-specific reference costs were applied. HrQoL was assessed prospectively in a separate cohort of 30 patients hospitalised with CDI, who completed the EQ-5D-3L questionnaire during their illness. Results: The median total management cost (post-index) was £7,539 and £6,294 for rCDI and fCDI, respectively (cost difference, p=0.075); median length of stay (LOS) was 21 days and 15.5 days, respectively (p=0.269). The median cost difference between matched rCDI and fCDI cases was £689 (IQR=£-1,873-£3,954). Subgroup analysis demonstrated the highest median costs (£8,542/patient) in severe rCDI cases. CDI management costs were driven primarily by hospital LOS, which accounted for >85% of costs in both groups. Mean EQ-5D index values were 46% lower in CDI patients compared with UK population values (0.42 and 0.78, respectively); EQ-VAS scores were 38% lower (47.82 and 77.3, respectively). Conclusions: CDI has considerable impact on patients and healthcare resources. This multicentre study provides a contemporaneous estimate of the real-world UK costs associated with rCDI management, which are substantial and comparable to fCDI costs