Viscous damping of roll during entry of a Mars entry and landing capsule

Viscous damping in roll of blunt body and hemisphere-cone forebody during planetary entr

A review of aerodynamic noise from propellers, rotors, and lift fans

Hand calculation procedures for predicting aerodynamic noise from propellers, rotors, and lift fan

Low subsonic dynamic-stability investigation of several planetary-entry configurations in a vertical wind tunnel, part i

Low subsonic dynamic stability data for evaluation of ballistic deceleration vehicle entering Mars atmospher

Wind Field and Trajectory Models for Tornado-Propelled Objects

A mathematical model to predict the trajectory of tornado born objects postulated to be in the vicinity of nuclear power plants is developed. An improved tornado wind field model satisfied the no slip ground boundary condition of fluid mechanics and includes the functional dependence of eddy viscosity with altitude. Subscale wind tunnel data are obtained for all of the missiles currently specified for nuclear plant design. Confirmatory full-scale data are obtained for a 12 inch pipe and automobile. The original six degree of freedom trajectory model is modified to include the improved wind field and increased capability as to body shapes and inertial characteristics that can be handled. The improved trajectory model is used to calculate maximum credible speeds, which for all of the heavy missiles are considerably less than those currently specified for design. Equivalent coefficients for use in three degree of freedom models are developed and the sensitivity of range and speed to various trajectory parameters for the 12 inch diameter pipe are examined

Applications of aerospace technology to petroleum extraction and reservoir engineering

Through contacts with the petroleum industry, the petroleum service industry, universities and government agencies, important petroleum extraction problems were identified. For each problem, areas of aerospace technology that might aid in its solution were also identified, where possible. Some of the problems were selected for further consideration. Work on these problems led to the formulation of specific concepts as candidate for development. Each concept is addressed to the solution of specific extraction problems and makes use of specific areas of aerospace technology

Orbital angular momentum exchange in an optical parametric oscillator

We present a study of orbital angular momentum transfer from pump to down-converted beams in a type-II Optical Parametric Oscillator. Cavity and anisotropy effects are investigated and demostrated to play a central role in the transverse mode dynamics. While the idler beam can oscillate in a Laguerre-Gauss mode, the crystal birefringence induces an astigmatic effect in the signal beam that prevents the resonance of such mode.Comment: 10 pages, 8 figures, regular articl

Transients in Power Systems

Power system engineering largely focuses on steady state analysis. The main areas of power system engineering are power flow studies and fault studies - both steady state technologies. But the world is largely transient, and power systems are always subject to time varying and short lived signals. This technical report concerns several important topics in transient analyses of power systems. The leading chapter deals with a new analytical tool-wavelets-for power system transients. Flicker and electric are furnace transients are discussed in Chapters I1 and IV. Chapter 111 deals with transients from shunt capacitor switching. The concluding chapters deal with transformer inrush current and non simultaneous pole closures of circuit breakers. This report was prepared by the students in EE532 at Purdue University. When I first came to Purdue in 1965, Professor El-Abiad was asking for student term projects which were turned into technical reports. I have \u27borrowed\u27 this idea and for many years we have produced technical reports from the power systems courses. The students get practice in writing reports, and the reader is able to get an idea of the coverage of our courses. I think that the students have done a good job on the subject of transients in power systems

The Impact of COVID-19-Induced Changes at Schools on Elementary Students' School Engagement

In spring 2020, the COVID-19 pandemic led to the shutdown of schools in many countries. Emerging research documents the negative effects of the pandemic and particularly of the shutdown of schools on children's well-being. The present research extends this research by investigating how structural changes made in schools upon reopening to align with COVID-19 restrictions were related to children's emotional school engagement and subjective well-being. An online questionnaire with elementary school children and their parents conducted in Norway in June 2020 (N = 93 parent–child dyads; 46 boys, 47 girls; mean age children = 9.70 years, SD = 1.81) assessed structural changes in schools and children's coping with these changes, emotional school engagement, subjective well-being, self-reported performance in school, and demographics. Results showed that neither receiving a new teacher nor being assigned to a new (smaller) group were associated with negative outcomes. However, children who did not like their new group showed reduced emotional school engagement and subjective well-being, indicating that specific students particularly suffered from the pandemic-induced restrictions. The relationship between liking one's group and SWB was mediated by emotional school engagement. Applied and theoretical implications are discussed

Wave Packet Echoes in the Motion of Trapped Atoms

We experimentally demonstrate and systematically study the stimulated revival (echo) of motional wave packet oscillations. For this purpose, we prepare wave packets in an optical lattice by non-adiabatically shifting the potential and stimulate their reoccurence by a second shift after a variable time delay. This technique, analogous to spin echoes, enables one even in the presence of strong dephasing to determine the coherence time of the wave packets. We find that for strongly bound atoms it is comparable to the cooling time and much longer than the inverse of the photon scattering rate

What do I want to be? Predictors of communal occupational aspirations in early to middle childhood

Research investigating occupational aspirations in childhood is scarce. In addition, most research on occupational aspirations has focused on increasing the number of women in agentic jobs. In the present work, we investigate factors associated with communal occupational aspirations in two studies with young children (Study 1: 159 children [84 boys, 75 girls], Mage = 5.51 years, SD = 0.37; Study 2: 96 children [48 boys, 48 girls]; Mage = 9.44 years, SD = 1.91). We found gender differences in communal aspirations only among the older children. In both samples, as well as when combining the two samples, the stronger the communal occupational gender stereotypes children reported, the less boys (and the more girls) aspired toward communal occupations. In the combined sample, communal self-perceptions mediated the relationship between child gender and occupational aspirations. Finally, the perceived status of the occupations was positively associated with communal aspirations among older children