Dynamic analysis of geared rotors by finite elements

A finite-element model of a geared rotor system on flexible bearings was developed. The model includes the rotary inertia of shaft elements, the axial loading on shafts, flexibility and damping of bearings, material damping of shafts and the stiffness and the damping of gear mesh. The coupling between the torsional and transverse vibrations of gears were considered in the model. A constant mesh stiffness was assumed. The analysis procedure can be used for forced vibration analysis of geared rotors by calculating the critical speeds and determining the response of any point on the shaft to mass unbalances, geometric eccentricities of gears and displacement transmission error excitation at the mesh point. The dynamic mesh forces due to these excitations can also be calculated. The model has been applied to several systems for the demonstration of its accuracy and for studying the effect of bearing compliances on system dynamics

Growth and Characterization of CuO Nanostructures on Si for the Fabrication of CuO/p-Si Schottky Diodes

CuO interlayers in the CuO/p-Si Schottky diodes were fabricated by using CBD and sol-gel methods. Deposited CuO layers were characterized by SEM and XRD techniques. From the SEM images, it was seen that the film grown by CBD method is denser than the film grown by sol-gel method. This result is compatible with XRD results which show that the crystallization in CBD method is higher than it is in sol-gel method. For the electrical investigations, current-voltage characteristics of the diodes have been studied at room temperature. Conventional I-V and Norde’s methods were used in order to determine the ideality factor, barrier height, and series resistance values. It was seen that the morphological and structural analysis are compatible with the results of electrical investigations

Pathways to Family Success Final Evaluation Report

This report presents findings from the second year of the evaluation of the Pathways to Family Success Programs (PFS) funded by the Department of Elementary and Secondary Education (ESE) and conducted by the Center for Social Policy (CSP) for the period September 2010 through June 2011. The 2010-2011 evaluation aimed to determine the extent to which PFS activities and interventions were effective in supporting learning outcomes and goal attainment for participating families and their children, and to identify strengths and areas of growth for the PFS Programs and partners. There were four Program sites implementing the PFS indepth project during the second year evaluation period. These leading agencies for the PFS sites included the following: Cambridge Community Learning Center Greater Lawrence Community ActionCouncil, Inc. Holyoke Public Schools Berkshire Children and Families, Inc. The evaluation design involved gathering information on three different outcome levels: the first level includes outcomes for adults, children and families; the second includes outcomes at the program level, and the third focuses on outcomes for the community partnership as a whole. The evaluation utilized a mixed-method approach including both qualitative and quantitative methods and a range of data sources to answer the research questions related to the PFS indepth projects and community partnerships. The evaluation team also conducted case studies of a sample of Pathways Families by interviewing two families from each Pathways site at two points in time

Massachusetts Adult Basic Education and ESOL Distance Learning Programs: How to Assess Student Readiness for Distance Learning?

This report presents the findings from the pilot screening process prepared by the Center for Social Policy (CSP) and implemented during December 2008-March 2009 by the adult basic education (ABE) online learning programs in MA which are funded by the Department of Elementary and Secondary Education (ESE). The purposes of the pilot process were: To determine the effectiveness of screening tools in assessing participant characteristics, such as the skills, demographics, and life circumstances that are associated with success in online learning; To identify supports and interventions which students need in order to persist and succeed in online learning. At the end of the first round of research during April-August 2008, CSP research team determined that readiness and success of adult students in online learning are embedded indeed in multiple factors both at the individual and the contextual level and these multiple factors are inter-connected with one another. The individual factors include various demographic variables, social characteristics, life situations, learning styles, motivation, computer skills, and cognitive and meta-cognitive skills. The contextual factors include the role of the instructor, the variability and access to the materials and technology being used, the type of program, i.e. GED, Pre-GED and ESOL, the specific requirements of the course being taught and the curriculum design (Petty, Johnston, & Shafer, 2004). CSP researchers developed the Interactive-Constructivist Model of ABE Distance Learning (DL) based on the findings of the first round of research. The Interactive-Constructivist approach conceives learning as a social process. Learning does not happen in a vacuum, but rather in a social context (Kahraman, Mallona, Friedman, Platt, & Kahan, 2008)

Spectroscopic Survey of {\gamma} Doradus Stars I. Comprehensive atmospheric parameters and abundance analysis of {\gamma} Doradus stars

We present a spectroscopic survey of known and candidate $\gamma$\,Doradus stars. The high-resolution, high signal-to-noise spectra of 52 objects were collected by five different spectrographs. The spectral classification, atmospheric parameters (\teff, $\log g$, $\xi$), $v\sin i$ and chemical composition of the stars were derived. The stellar spectral and luminosity classes were found between G0-A7 and IV-V, respectively. The initial values for \teff\ and \logg\ were determined from the photometric indices and spectral energy distribution. Those parameters were improved by the analysis of hydrogen lines. The final values of \teff, \logg\ and $\xi$ were derived from the iron lines analysis. The \teff\ values were found between 6000\,K and 7900\,K, while \logg\,values range from 3.8 to 4.5\,dex. Chemical abundances and $v\sin i$ values were derived by the spectrum synthesis method. The $v\sin i$ values were found between 5 and 240\,km\,s$^{-1}$. The chemical abundance pattern of $\gamma$\,Doradus stars were compared with the pattern of non-pulsating stars. It turned out that there is no significant difference in abundance patterns between these two groups. Additionally, the relations between the atmospheric parameters and the pulsation quantities were checked. A strong correlation between the $v\sin i$ and the pulsation periods of $\gamma$\,Doradus variables was obtained. The accurate positions of the analysed stars in the H-R diagram have been shown. Most of our objects are located inside or close to the blue edge of the theoretical instability strip of $\gamma$\,Doradus.Comment: 18 pages, 13 figure

X-Ray Microscopy of Spin Wave Focusing using a Fresnel Zone Plate

Magnonics, i.e. the artificial manipulation of spin waves, is a flourishing field of research with many potential uses in data processing within reach. Apart from the technological applications the possibility to directly influence and observe these types of waves is of great interest for fundamental research. Guidance and steering of spin waves has been previously shown and lateral spin wave confinement has been achieved. However, true spin wave focusing with both lateral confinement and increase in amplitude has not been shown before. Here, we show for the first time spin wave focusing by realizing a Fresnel zone plate type lens. Using x-ray microscopy we are able to directly image the propagation of spin waves into the nanometer sized focal spot. Furthermore, we observe that the focal spot can be freely moved in a large area by small variations of the bias field. Thus, this type of lens provides a steerable intense nanometer sized spin wave source. Potentially, this could be used to selectively illuminate magnonic devices like nano oscillators with a steerable spin wave beam