An optimization study to minimize surface distortions of a hoop-column antenna

An automated procedure to lessen the tedium of manual approach currently used to minimize surface distortions in a hoop/column antenna is studied. Three fundamental elements are used for the study: (1) The finite element analysis program is used to calculate the antenna surface distortions due to externally applied loads; (2) a general purpose optimization program is used to determine the set of control cable tensions which minimize the antenna surface distortions; and (3) another program is used to calculate the best fit parabola passing through a distorted antenna shape and to calculate the RMS distortion error. The interim results of this feasibility study are given

Multidisciplinary optimization applied to a transport aircraft

Decomposition of a large optimization problem into several smaller subproblems has been proposed as an approach to making large-scale optimization problems tractable. To date, the characteristics of this approach have been tested on problems of limited complexity. The objective of the effort is to demonstrate the application of this multilevel optimization method on a large-scale design study using analytical models comparable to those currently being used in the aircraft industry. The purpose of the design study which is underway to provide this demonstration is to generate a wing design for a transport aircraft which will perform a specified mission with minimum block fuel. A definition of the problem; a discussion of the multilevel composition which is used for an aircraft wing; descriptions of analysis and optimization procedures used at each level; and numerical results obtained to date are included. Computational times required to perform various steps in the process are also given. Finally, a summary of the current status and plans for continuation of this development effort are given

Spatial Heterogeneity, Accessibility and Zoning: An Empirical Investigation of Leapfrog Development

Using data on subdivision development from 1960 to 2005 in the Baltimore, Maryland region, we develop a new, subdivision-specific measure of leapfrog development. Applying this measure, we find that about 80% of developable land that was more accessible to the urban center than newly built subdivisions remained undeveloped as of 1960. This amount declined by more than 50% over our 45-year study period to 36% in 2005. We compare this pattern with a hypothesized pattern generated by a parameterized intertemporal urban growth model and find that the observed pattern is consistent with urban economic theory, including the implied effects of zoning. Specifically, by fixing the allowable development density, low-density zoning eliminates the incentive to withhold more accessible land and thus reduces leapfrog development, a prediction that we confirm empirically. The results illustrate the efficacy of the urban growth model and the substantial influence of spatially heterogeneous zoning on urban land development patterns

Integrating aerodynamics and structures in the minimum weight design of a supersonic transport wing

An approach is presented for determining the minimum weight design of aircraft wing models which takes into consideration aerodynamics-structure coupling when calculating both zeroth order information needed for analysis and first order information needed for optimization. When performing sensitivity analysis, coupling is accounted for by using a generalized sensitivity formulation. The results presented show that the aeroelastic effects are calculated properly and noticeably reduce constraint approximation errors. However, for the particular example selected, the error introduced by ignoring aeroelastic effects are not sufficient to significantly affect the convergence of the optimization process. Trade studies are reported that consider different structural materials, internal spar layouts, and panel buckling lengths. For the formulation, model and materials used in this study, an advanced aluminum material produced the lightest design while satisfying the problem constraints. Also, shorter panel buckling lengths resulted in lower weights by permitting smaller panel thicknesses and generally, by unloading the wing skins and loading the spar caps. Finally, straight spars required slightly lower wing weights than angled spars

A solar cycle of spacecraft anomalies due to internal charging

International audienceIt is important to appreciate how the morphology of internal charging of spacecraft systems, due to penetrating electrons, differs from that of the more common surface charging, due to electrons with lower energy. A specific and recurrent anomaly on a geostationary communication satellite has been tracked for ten years so that solar cycle and seasonal dependencies can be clearly established. Concurrent measurements of sunspot number, solar wind speed and 2-day >2 MeV electron fluence are presented to highlight pertinent space weather relationships, and the importance of understanding the complex particle interaction processes involved

Application of multidisciplinary optimization methods to the design of a supersonic transport

An optimization design method is discussed. This method is based on integrating existing disciplinary analysis and sensitivity analysis techniques by means of generalized sensitivity equations. A generic design system implementing this method is described. The system is being used to design the configuration and internal structure of a supersonic transport wing for optimum performance. This problem combines the disciplines of linear aerodynamics, structures, and performance. Initial results which include the disciplines of aerodynamics and structures in a conventional minimum weight design under static aeroelastic constraints are presented

Experimental evidence of an electron temperature enhancement in the wake of an ionospheric satellite

A study of electron temperature (Te) measurements made by a Langmuir probe mounted on the skin of the Explorer 31 satellite indicates that electron temperature in the very near wake exceeds that of the ambient electron gas. Potential causes of such an enhancement are mentioned but the possibility that the wake `temperatures' reflect the existence of non-Maxwellian energy distributions cannot be discounted. The results are compared with observations from the Gemini/Agena wake experiment and are found to be in reasonable agreement.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34096/1/0000378.pd

Resilience: Protective Factors for Depression and Post Traumatic Stress Disorder among African American Women?

There is a great need to carefully examine issues that may elevate one’s risk for mental illness and develop strategies to mitigate risk and cultivate resilience.  African Americans, specifically African American women (AAW), are disproportionately affected by mental illness, including depression and post-traumatic stress disorder (PTSD).  Higher rates of PTSD among AAW may be explained by significant rates of trauma exposure.  Higher resiliency in individuals with mental illnesses is associated with better treatment response/outcomes.  An examination of two (2) promising psycho-educational curricula for AAW at risk for depression and PTSD supports consideration of resilience as a protective factor among this population.  Strengthening psychological resilience among diverse AAW at risk for depression and/or PTSD may serve as a protective factor for symptom severity.  Multidimensional prevention and intervention strategies should incorporate culturally-centered, gender-specific, and strengths-based (resilience) models of care to help encourage mental health help-seeking and promotion of wellness for AAW