Emitted vibration measurement device and method

This invention is directed to a method and apparatus for measuring emitted vibrational forces produced by a reaction wheel assembly due to imbalances, misalignment, bearing defects and the like. The apparatus includes a low mass carriage supported on a large mass base. The carriage is in the form of an octagonal frame having an opening which is adapted for receiving the reaction wheel assembly supported thereon by means of a mounting ring. The carriage is supported on the base by means of air bearings which support the carriage in a generally frictionless manner when supplied with compressed air from a source. A plurality of carriage brackets and a plurality of base blocks provided for physical coupling of the base and carriage. The sensing axes of the load cells are arranged generally parallel to the base and connected between the base and carriage such that all of the vibrational forces emitted by the reaction wheel assembly are effectively transmitted through the sensing axes of the load cells. In this manner, a highly reliable and accurate measurment of the vibrational forces of the reaction wheel assembly can be had. The output signals from the load cells are subjected to a dynamical analyzer which analyzes and identifies the rotor and spin bearing components which are causing the vibrational forces

Measurement of the earthshine polarization in the B, V, R, and I band as function of phase

The characterization of the polarimetric properties of the planet Earth is important for the interpretation of expected observations and the planning of future instruments. We present a multi-wavelengths and multi-phase set of benchmark values for the polarization signal of the integrated light from the planet Earth derived from new polarimetric observations of the earthshine back-scattered from the Moon's dark side. Using a new, specially designed wide field polarimeter we measured the fractional polarization of the earthshine in the B, V, R and I filters for Earth phase angles alpha between 30{\deg} and 110{\deg}. The phase dependence of the earthshine polarization is fitted by a function p x sin(alpha)^2. To determine the polarization of the planet Earth we correct our earthshine measurements by a polarization efficiency function for the lunar surface derived from measurements of lunar samples from the literature. The polarization of the earthshine decreases towards longer wavelengths and is about a factor 1.3 lower for the higher albedo highlands. For mare regions the measured maximum polarization is about 13 % at quadrature in the B band. The resulting fractional polarizations for Earth are 24.6 % for the B band, 19.1 % for the V band, 13.5 % for the R band, and 8.3 % for the I band. Together with literature values for the spectral reflectivity of Earth we obtain a contrast between the polarized flux of the Earth and the (total) flux of the Sun with an uncertainty of less than 20 % and we find that the best phase to detect an Earth twin is around an Earth phase alpha=65{\deg}. The polarimetric models of Earth-like planets from Stam (2008) are in qualitative agreement with our results but there are also significant differences which might guide more detailed computations.Comment: 14 pages, 14 figures, accepted for publication in Astronomy & Astrophysic

The Estimation Error in the Chain-Ladder Reserving Method: A Bayesian Approach

We derive the estimation error in a Bayesian framework and discuss the estimates of Mack and of Buchwalder, Bühlmann, Merz and Wüthrich (BBMW) from a Bayesian point of vie

Rhythmic cluster generation in strongly driven colloidal dispersions

We study the response of a nematic colloidal dispersion of rods to a driven probe particle which is dragged with high speed through the dispersion perpendicular to the nematic director. In front of the dragged particle, clusters of rods are generated which rhythmically grow and dissolve by rotational motion. We find evidence for a mesoscopic cluster-cluster correlation length, {\em independent} of the imposed drag speed. Our results are based on non-equilibrium Brownian dynamics computer simulations and in line with a dynamical scaling theory.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let

COMPETITIVE FOOD POLICY IMPLEMENTATION IN KENTUCKY SCHOOLS

This study was designed to explore the literature on competitive food policy implementation (CFPI); examines demographic and school factors associated with CFPI; and explores the experiences of school leaders and staff in CFPI using a proposed theoretical framework to guide the research. Competitive foods are those sold in vending machines, a la carte settings, fundraisers, class parties and other venues which compete with foods offered through the national school lunch and breakfast programs. Competitive foods have traditionally been of low nutritional value and high energy density. CFPI may be effective in reducing student calorie intake and BMI. However, evaluation of competitive food policy effectiveness is difficult due to variability in policy implementation. A theoretical framework is needed to guide research on CFPI. This research was a mixed methods study including a review of the literature, quantitative secondary analysis, and a qualitative content analysis of transcripts from semi-structured interviews with school personnel to understand their experience with CFPI. First, a systematic review of the research literature on CFPI was conducted. Demographic and school factors, policy features, and school and parent/community-level factors that impact CFPI were identified. Second, the association of multiple demographic and school factors with CFPI scores was examined. CFPI scale (overall) and sub-scales (“inside” and “outside” school) were developed and validated to evaluate CFPI effectiveness in Kentucky middle and high schools (N=640, grades 5-12). The scales were based on responses to 8 questions on competitive food practices from a 2011 School Tobacco and Wellness Policy biannual survey conducted by the University Of Kentucky College Of Nursing Tobacco Policy Research Program. Student BMI tracking and presence of a written wellness policy predicted higher scores on the overall CFPI scale (BMI OR=2.06, p=0.001; Wellness OR=1.74, p=0.02), inside subscale scores (BMI OR=2.46, p\u3c0.0001; Wellness OR=1.58, p=0.05), and outside subscale scores (BMI OR=2.27, p=0.03; Wellness OR=1.54, p=0.0005). Greater county-level adult obesity rates predicted lower overall CFPI scores (OR=0.93, p=0.02). Private school status predicted lower scores on inside CFPI subscale scores (OR=0.47, p=0.004). Third, semi-structured interviews were conducted with 23 school personnel to explore CFPI. Interviews were recorded, transcribed and content analysis was conducted. Kentucky schools were stratified into four groups based on school level (middle or high) and CFPI scores (high or low). Sixteen schools were randomly selected for each of the four groups. A total of eight schools, two from each group, agreed to participate. The interview guide was based on a proposed CFPI framework based on implementation science, educational and organizational theory research. Six key themes emerged: internal/external forces enabling CFPI; internal and external obstacles to CFPI; key organizational values; organization value of CFPI; methods that organizations use to communicate organizational values; and CFPI policies and procedures. Findings were discussed in the context of the proposed theoretical framework. Implications for policy, practice and future research are presented