Numerical methods for the design and analysis of wings at supersonic speeds

Numerical methods for the design and analysis of arbitrary-planform wings at supersonic speeds are reviewed. Certain deficiencies are revealed, particularly in application to wings with slightly subsonic leading edges. Recently devised numerical techniques which overcome the major part of these deficiencies are presented. The original development as well as the more recent revisions are subjected to a thorough review

Electron densities and temperatures in the f-region from backscatter measurements at arecibo

Diurnal variation in electron densities and temperatures in F region from backscatter measurements over Puerto Ric

Mechanisms of wave transformation in finite-depth water

Mechanisms of wave transformation in finite-depth water are investigated. The linear mechanisms ex- amined are percolation, bottom motion, shoaling, and refraction. The nonlinear mechanisms examined are wave-wave interaction and bottom friction. New exact computations of the nonlinear transfer for fi- nite-depth waves are presented for some directional wave spectra. These mechanisms are found to ex- plain satisfactorily wave decay observations obtained at several sites with different bottom sediment properties. The decay rates at these sites are found to be dominated by different mechanisms which are determined by the bottom conditions. As an example, detailed calculations are presented for data ob- tained at the Jonswap site

A linearized theory method of constrained optimization for supersonic cruise wing design

A linearized theory wing design and optimization procedure which allows physical realism and practical considerations to be imposed as constraints on the optimum (least drag due to lift) solution is discussed and examples of application are presented. In addition to the usual constraints on lift and pitching moment, constraints are imposed on wing surface ordinates and wing upper surface pressure levels and gradients. The design procedure also provides the capability of including directly in the optimization process the effects of other aircraft components such as a fuselage, canards, and nacelles

DOES MOTHER KNOW BEST?: A COMPARISON OF BIOLOGICAL AND SOCIAL FATHERS AFTER A NONMARITAL BIRTH

High rates of nonmarital childbearing combined with high rates of instability and repartnering in nonmarital relationships portend that a large proportion of children born to unmarried mothers can expect to spend time with a ‘social father.’ This paper uses data from the Fragile Families and Child Wellbeing Study to examine the prevalence and characteristics of social fathers during the first three years following a nonmarital birth. The results indicate that 22% of unmarried mothers have formed new partnerships by the time their child is age three, and 12% are living with their new partners. The results also indicate that re-partnering represents a gain for most mothers and children in terms of fathers’ human capital and pro-social behavior. Our findings are consistent with the idea that unmarried mothers continue to search for ‘good fathers’ after their children are born and that many of these women are successful in their search.

Stick-Slip Motion and Phase Transition in a Block-Spring System

We study numerically stick slip motions in a model of blocks and springs being pulled slowly. The sliding friction is assumed to change dynamically with a state variable. The transition from steady sliding to stick-slip is subcritical in a single block and spring system. However, we find that the transition is continuous in a long chain of blocks and springs. The size distribution of stick-slip motions exhibits a power law at the critical point.Comment: 8 figure

Weak phase separation and the pseudogap in the electron-doped cuprates

We study the quantum transition from an antiferromagnet to a superconductor in a model for electron- and hole-doped cuprates by means of a variational cluster perturbation theory approach. In both cases, our results suggest a tendency towards phase separation between a mixed antiferromagnetic-superconducting phase at low doping and a pure superconducting phase at larger doping. However, in the electron-doped case the energy scale for phase separation is an order of magnitude smaller than for hole doping. We argue that this can explain the different pseudogap and superconducting transition scales in hole- and electron-doped materials.Comment: Final version, accepted for publication in Europhysics Letter

Income Sustainability through Educational Attainment

The authors examined the sustainability of income, as it relates to educational attainment, from the two recent decades, which includes three significant economic downturns. The data was analyzed to determine trends in the wealth gap, parsed by educational attainment and gender. Utilizing the data from 1991 through 2010, predictions in changes in the wealth gap and standard of living, as it relates to educational attainment, was made through the year 2030. The research supported a positive correlation between education levels and salaries, independent of economic conditions in the United States. Thus, the higher the education level achieved, the higher the earnings, and the lower the volatility during periods of economic downturn. Furthermore, the results indicated that a Bachelor Degree only ensured equilibrium with inflationary increases over the two decades. The real earnings, adjusted for inflation, of all educational levels below the Bachelor’s Degree declined over the twenty year period. Thus, the wealth gap is increasing as real earnings have stayed constant or declined for nearly 90% of all workers in the United States. In addition, while there is still a significant gap between female and male earnings, females fared significantly better than their male counterparts, in terms of changes in annual earning’s. The predictions have shown that the wealth gap will continue to widen over the next two decades, based on current trends. In general terms, the authors conclude that the buying power and standard of living in the United States is declining for all education levels below a Bachelor’s Degree