Longitudinal vibration of ring stiffened cylindrical shells containing liquids Technical report no. 7

Longitudinal vibration of ring stiffened cylindrical shells containing liquids for application to liquid fueled space vehicle booster

A random walk model to study the cycles emerging from the exploration-exploitation trade-off

We present a model for a random walk with memory, phenomenologically inspired in a biological system. The walker has the capacity to remember the time of the last visit to each site and the step taken from there. This memory affects the behavior of the walker each time it reaches an already visited site modulating the probability of repeating previous moves. This probability increases with the time elapsed from the last visit. A biological analog of the walker is a frugivore, with the lattice sites representing plants. The memory effect can be associated with the time needed by plants to recover its fruit load. We propose two different strategies, conservative and explorative, as well as intermediate cases, leading to non intuitive interesting results, such as the emergence of cycles.Comment: To appear in Phys. Rev.

Trapping with biased diffusion species

We analyze a trapping reaction with a single penetrable trap, in a one dimensional lattice, where both species (particles and trap) are mobile and have a drift velocity. We obtain the density as seen from a reference system attached to the trap and from the laboratory frame. In addition we study the nearest neighbor distance to the trap. We exploit a stochastic model previously developed, and compare the results with numerical simulations, resulting in an excellent agreement.Comment: 6 pages, 7 Postscript figure

Some Notes on Liquid Sloshing in Compartmented Cylindrical Tanks Technical Report No. 1

Frequencies and total force response in rigid cylindrical tanks comparted into sectors by vertical walls and excited in translation to study liquid sloshin

Parenting Behaviors Related to Young Adult Depressive Symptomology

Parental stress, hostility, warmth, acceptance, amount of control, and overall security of parent-child attachment appears to influence childhood and adult adjustment. Several relationships have been found between parenting style and the emotional and psychological well being of children and adolescents (e.g., Baumrind, 1967, 1971; Parker, 1979a, 1979b; Ge, Conger, Lorenz, & Simons, 1994; Ge, Best, Conger, & Simons, 1996). The present study examined the effects of perceived parenting styles on young adults\u27 reported psychological distress and depressive symptomology. Participants viewed both mothers and fathers as equally attentive, supportive, and controlling, while viewing mothers as slightly more caring. However, participants\u27 perceptions of their mothers\u27 parenting practices showed strong relationships to respondents\u27 reported depressive symptomology and stress levels while their perceptions of their fathers showed weak relationships to stress and depressive symptomology. Parenting style was assessed using the Parental Bonding Instrument (Parker, Tupling, & Brown, 1979) and the Children\u27s Report of Parenting Behavior Inventory (Schaefer, 1965). Psychological distress and level of depressive symptomology were measured with the Symptom-Checklist-90-Revised (Derogatis, 1983) and the Center for Epidemiologic Studies-Depression-Scale (Radloff; 1977)

A simplex-like search method for bi-objective optimization

We describe a new algorithm for bi-objective optimization, similar to the Nelder Mead simplex algorithm, widely used for single objective optimization. For diferentiable bi-objective functions on a continuous search space, internal Pareto optima occur where the two gradient vectors point in opposite directions. So such optima may be located by minimizing the cosine of the angle between these vectors. This requires a complex rather than a simplex, so we term the technique the \cosine seeking complex". An extra beneft of this approach is that a successful search identifes the direction of the effcient curve of Pareto points, expediting further searches. Results are presented for some standard test functions. The method presented is quite complicated and space considerations here preclude complete details. We hope to publish a fuller description in another place