Automobile ride quality experiments correlated to iso-weighted criteria

As part of an overall study to evaluate the usefulness of ride quality criteria for the design of improved ground transportation systems an experiment was conducted involving subjective and objective measurement of ride vibrations found in an automobile riding over roadways of various roughness. Correlation of the results led to some very significant relationships between passenger rating and ride accelerations. The latter were collapsed using a frequency-weighted root mean square measure of the random vibration. The results suggest the form of a design criterion giving the relationship between ride vibration and acceptable automobile ride quality. Further the ride criterion is expressed in terms that relate to rides with which most people are familiar. The design of the experiment, the ride vibration data acquisition, the concept of frequency weighting and the correlations found between subjective and objective measurements are presented

TDAS: The Thermal Expert System (TEXSYS) data acquisition system

As part of the NASA Systems Autonomy Demonstration Project, a thermal expert system (TEXSYS) is being developed. TEXSYS combines a fast real time control system, a sophisticated human interface for the user and several distinct artificial intelligence techniques in one system. TEXSYS is to provide real time control, operations advice and fault detection, isolation and recovery capabilities for the space station Thermal Test Bed (TTB). TEXSYS will be integrated with the TTB and act as an intelligent assistant to thermal engineers conducting TTB tests and experiments. The results are presented from connecting the real time controller to the knowledge based system thereby creating an integrated system. Special attention will be paid to the problem of filtering and interpreting the raw, real time data and placing the important values into the knowledge base of the expert system

Magnetic field tuning of coplanar waveguide resonators

We describe measurements on microwave coplanar resonators designed for quantum bit experiments. Resonators have been patterned onto sapphire and silicon substrates, and quality factors in excess of a million have been observed. The resonant frequency shows a high sensitivity to magnetic field applied perpendicular to the plane of the film, with a quadratic dependence for the fundamental, second and third harmonics. Frequency shift of hundreds of linewidths can be obtained.Comment: Accepted for publication in AP

On the properties of superconducting planar resonators at mK temperatures

Planar superconducting resonators are now being increasingly used at mK temperatures in a number of novel applications. They are also interesting devices in their own right since they allow us to probe the properties of both the superconductor and its environment. We have experimentally investigated three types of niobium resonators - including a lumped element design - fabricated on sapphire and SiO_2/Si substrates. They all exhibit a non-trivial temperature dependence of their centre frequency and quality factor. Our results shed new light on the interaction between the electromagnetic waves in the resonator and two-level fluctuators in the substrate.Comment: V2 includes some minor corrections/changes. Submitted to PR

Circuit QED with a Flux Qubit Strongly Coupled to a Coplanar Transmission Line Resonator

We propose a scheme for circuit quantum electrodynamics with a superconducting flux-qubit coupled to a high-Q coplanar resonator. Assuming realistic circuit parameters we predict that it is possible to reach the strong coupling regime. Routes to metrological applications, such as single photon generation and quantum non-demolition measurements are discussed.Comment: 8 pages, 5 figure

A Statistical Description of AGN Jet Evolution from the VLBA Imaging and Polarimetry Survey (VIPS)

A detailed analysis of the evolution of the properties of core-jet systems within the VLBA Imaging and Polarimetry Survey (VIPS) is presented. We find a power-law relationship between jet intensity and width that suggests for the typical jet, little if any energy is lost as it moves away from its core. Using VLA images at 1.5 GHz, we have found evidence that parsec-scale jets tend to be aligned with the the direction of emission on kiloparsec scales. We also found that this alignment improves as the jets move farther from their cores on projected scales as small as ~50-100 pc. This suggests that realignment of jets on these projected scales is relatively common. We typically find a modest amount of bending (a change in jet position angle of ~5 deg.) on these scales, suggesting that this realignment may typically occur relatively gradually.Comment: Accepted to ApJ, 20 pages, 8 figure

The Impact of Shape on the Perception of Euler Diagrams

Euler diagrams are often used for visualizing data collected into sets. However, there is a significant lack of guidance regarding graphical choices for Euler diagram layout. To address this deficiency, this paper asks the question `does the shape of a closed curve affect a user's comprehension of an Euler diagram?' By empirical study, we establish that curve shape does indeed impact on understandability. Our analysis of performance data indicates that circles perform best, followed by squares, with ellipses and rectangles jointly performing worst. We conclude that, where possible, circles should be used to draw effective Euler diagrams. Further, the ability to discriminate curves from zones and the symmetry of the curve shapes is argued to be important. We utilize perceptual theory to explain these results. As a consequence of this research, improved diagram layout decisions can be made for Euler diagrams whether they are manually or automatically drawn

Characteristics of Gamma-Ray Loud Blazars in the VLBA Imaging and Polarimetry Survey

The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed as part of the VLBA Imaging and Polarimetry Survey (VIPS). This large, flux-limited sample of active galactic nuclei (AGN) provides insights into the mechanism that produces strong gamma-ray emission. At lower flux levels, radio flux density does not directly correlate with gamma-ray flux. We find that the LAT-detected BL Lacs tend to be similar to the non-LAT BL Lacs, but that the LAT-detected FSRQs are often significantly different from the non-LAT FSRQs. The differences between the gamma-ray loud and quiet FSRQs can be explained by Doppler boosting; these objects appear to require larger Doppler factors than those of the BL Lacs. It is possible that the gamma-ray loud FSRQs are fundamentally different from the gamma-ray quiet FSRQs. Strong polarization at the base of the jet appears to be a signature for gamma-ray loud AGN.Comment: 32 pages, 9 figures, accepted by Ap

An intelligent, free-flying robot

The ground based demonstration of the extensive extravehicular activity (EVA) Retriever, a voice-supervised, intelligent, free flying robot, is designed to evaluate the capability to retrieve objects (astronauts, equipment, and tools) which have accidentally separated from the Space Station. The major objective of the EVA Retriever Project is to design, develop, and evaluate an integrated robotic hardware and on-board software system which autonomously: (1) performs system activation and check-out; (2) searches for and acquires the target; (3) plans and executes a rendezvous while continuously tracking the target; (4) avoids stationary and moving obstacles; (5) reaches for and grapples the target; (6) returns to transfer the object; and (7) returns to base

Outbreak of acute hepatitis C following the use of anti-hepatitis C virus--screened intravenous immunoglobulin therapy

BACKGROUND and AIMS: Hepatitis C virus (HCV) infection has been associated with intravenous (IV) immunoglobulin (Ig), and plasma donations used to prepare IV Ig are now screened to prevent transmission. Thirty-six patients from the United Kingdom received infusions from a batch of anti-HCV antibody-screened intravenous Ig (Gammagard; Baxter Healthcare Ltd., Thetford, Norfolk, England) that was associated with reports of acute hepatitis C outbreak in Europe. The aim of this study was to document the epidemiology of this outbreak. METHODS: Forty-six patients from the United Kingdom treated with Gammagard (34 exposed and 12 unexposed to the batch) returned epidemiological questionnaires. RESULTS: Eighty-two percent of the exposed patients (28 of 34) became positive for HCV RNA. Eighteen percent of the patients (6 of 34) who had infusions with this batch tested negative for HCV RNA, but 2 of the patients had abnormal liver function and subsequently seroconverted to anti-HCV antibody positive. Twenty-seven percent of the patients (9 of 34) developed jaundice, and 79% (27 of 34) had abnormal liver transferase levels. Virus isolates (n=21), including an isolate from the implicated batch, were genotype 1a and virtually identical by sequence analysis of the NS5 region, consistent with transmission from a single source. CONCLUSIONS: Hepatitis C infection can be transmitted by anti-HCV-screened IV Ig. Careful documentation of IV Ig batch numbers and regular biochemical monitoring is recommended for all IV Ig recipients