Nondestructive testing techniques for multilayer printed wiring boards Final report, 30 Jun. 1964 - 30 Sep. 1965

Nondestructive testing techniques for laminated printed circuit board

Surface-peaked effective mass in the nuclear energy density functional and its influence on single-particle spectra

Calculations for infinite nuclear matter with realistic nucleon-nucleon interactions suggest that the isoscalar effective mass of a nucleon at the saturation density, m*/m, equals 0.8 +/- 0.1. This result is at variance with empirical data on the level density in finite nuclei, which are consistent with m*/m ~ 1. Ma and Wambach suggested that these two contradicting results may be reconciled within a single theoretical framework by assuming a radial-dependent effective mass, peaked at the nuclear surface. The aim of this exploratory work is to investigate this idea within the density functional theory by using a Skyrme-type local functional enriched with new terms, $\tau (\mathbf{\nabla}\rho)^2$ and $\tau\frac{d\rho}{dr}$, where $\tau$ and $\rho$ denote the kinetic and particle densities, respectively. We show that each of these terms can give rise to a surface peak in the effective mass, but of a limited height. We investigate the influence of the radial profile of the effective mass on the spin-orbit splittings and centroids. In particular, we demonstrate that the $\tau \frac{d\rho}{dr}$ term quenches the 1f5/2-1f7/2 splitting in 40Ca, which is strongly overestimated within conventional Skyrme parametrizations.Comment: 8 pages, 8 figures, submitted to Phys. Rev.

Bounds for the linear combinations of statistical tensors

A method of estimating the physical bounds for the linear combinations of components of statistical tensors is presented. Numerical values of the hounds for tensor combinations appearing in the additive quark model predictions for resonance production in two-body processes are calculated

Bonded and Stitched Composite Structure

A method of forming a composite structure can include providing a plurality of composite panels of material, each composite panel having a plurality of holes extending through the panel. An adhesive layer is applied to each composite panel and a adjoining layer is applied over the adhesive layer. The method also includes stitching the composite panels, adhesive layer, and adjoining layer together by passing a length of a flexible connecting element into the plurality of holes in the composite panels of material. At least the adhesive layer is cured to bond the composite panels together and thereby form the composite structure

ACT Payload Shroud Structural Concept Analysis and Optimization

Aerospace structural applications demand a weight efficient design to perform in a cost effective manner. This is particularly true for launch vehicle structures, where weight is the dominant design driver. The design process typically requires many iterations to ensure that a satisfactory minimum weight has been obtained. Although metallic structures can be weight efficient, composite structures can provide additional weight savings due to their lower density and additional design flexibility. This work presents structural analysis and weight optimization of a composite payload shroud for NASA s Ares V heavy lift vehicle. Two concepts, which were previously determined to be efficient for such a structure are evaluated: a hat stiffened/corrugated panel and a fiber reinforced foam sandwich panel. A composite structural optimization code, HyperSizer, is used to optimize the panel geometry, composite material ply orientations, and sandwich core material. HyperSizer enables an efficient evaluation of thousands of potential designs versus multiple strength and stability-based failure criteria across multiple load cases. HyperSizer sizing process uses a global finite element model to obtain element forces, which are statistically processed to arrive at panel-level design-to loads. These loads are then used to analyze each candidate panel design. A near optimum design is selected as the one with the lowest weight that also provides all positive margins of safety. The stiffness of each newly sized panel or beam component is taken into account in the subsequent finite element analysis. Iteration of analysis/optimization is performed to ensure a converged design. Sizing results for the hat stiffened panel concept and the fiber reinforced foam sandwich concept are presented

Methods for Assessing Honeycomb Sandwich Panel Wrinkling Failures

Efficient closed-form methods for predicting the facesheet wrinkling failure mode in sandwich panels are assessed. Comparisons were made with finite element model predictions for facesheet wrinkling, and a validated closed-form method was implemented in the HyperSizer structure sizing software

Shell evolution and nuclear forces

We present a quantitative study of the role played by different components characterizing the nucleon-nucleon interaction in the evolution of the nuclear shell structure. It is based on the spin-tensor decomposition of an effective two-body shell-model interaction and the subsequent study of effective single-particle energy variations in a series of isotopes or isotones. The technique allows to separate unambiguously contributions of the central, vector and tensor components of the realistic effective interaction. We show that while the global variation of the single-particle energies is due to the central component of the effective interaction, the characteristic behavior of spin-orbit partners, noticed recently, is mainly due to its tensor part. Based on the analysis of a well-fitted realistic interaction in sdpf-shell model space, we analyze in detail the role played by the different terms in the formation and/or disappearance of N=16, N=20 and N=28 shell gaps in neutron-rich nuclei.Comment: 6 pages, 4 figure

Tactical Athletes: An Integrated Approach to Understanding and Enhancing the Health and Performance of Firefighters-in-Training

International Journal of Exercise Science 8(4): 341-357, 2015. In an effort to reduce the rates of firefighter fatality, injury, and workplace stress, there has been a call for research to advance knowledge of firefighting performance and injury prevention. Physical and psychological variables important to firefighter health and performance have been identified, yet the interrelated nature of these variables has been overlooked. Given the overlap between the physical and psychological demands of firefighting and sport, and given that an integrated framework has been used in the sport domain to guide athlete health and performance research and practice, firefighter organizations could benefit from adopting a sport-based, integrated model of firefighter training and performance management. Guided by the Meyer Athlete Performance Management Model (MAPM), the purposes of the current study were to: (a) describe the physical and psychological characteristics of firefighters-in-training (i.e., cadets and recruits), and (b) explore relationships between the physical and psychological variables associated with health and performance. Firefighters-in-training employed by a Midwestern area fire department in the United States (N = 34) completed a battery of physical and psychological assessments at the department’s Fire and Safety Academy building. Results of the current study revealed significant correlations between several of the physical and psychological characteristics of firefighters-in-training. These results, along with the multidimensional data set that was also established in the current study, provide preliminary evidence for the use of a sport-based integrated performance model such as the MAPM to guide training and performance research in firefighter populations