GA tuning of pitch controller for small scale MAVs

The paper presents the application of intelligent tuning methods for the control of a prototype MAV in order to address problems associated with bandwidth limited actuators and gust alleviation. Specifically, as a proof of concept, the investigation is focused on the pitch control of a MAV. The work is supported by experimental results from wind tunnel testing that shows the merits of the use of Genetic Algorithm (GA) tuning techniques compared to classical, empirical tuning methodologies. To provide a measure of relative merit, the controller responses are evaluated using the ITAE performance index. In this way, the proposed method is shown to induce far superior dynamic performance compared to traditional approaches

Estimating the costs and benefits of providing free public transit passes to students in Los Angeles County: lessons learned in applying a health lens to decision-making.

In spite of increased focus by public health to engage and work with non-health sector partners to improve the health of the general as well as special populations, only a paucity of studies have described and disseminated emerging lessons and promising practices that can be used to undertake this work. This article describes the process used to conduct a Health Impact Assessment of a proposal to provide free public transportation passes to students in Los Angeles County. This illustrative case example describes opportunities and challenges encountered in working with an array of cross-sector partners and highlights four important lessons learned: (1) the benefits and challenges associated with broad conceptualization of public issues; (2) the need for more comprehensive, longitudinal data systems and dynamic simulation models to inform decision-making; (3) the importance of having a comprehensive policy assessment strategy that considers health impacts as well as costs and feasibility; and (4) the need for additional efforts to delineate the interconnectivity between health and other agency priorities. As public health advances cross-sector work in the community, further development of these priorities will help advance meaningful collaboration among all partners

Microscopic Restoration of Proton-Neutron Mixed Symmetry in Weakly Collective Nuclei

Starting from the microscopic low-momentum nucleon-nucleon interaction V{low k}, we present the first systematic shell model study of magnetic moments and magnetic dipole transition strengths of the basic low-energy one-quadrupole phonon excitations in nearly-spherical nuclei. Studying in particular the even-even N=52 isotones from 92Zr to 100Cd, we find the predicted evolution of the predominantly proton-neutron non-symmetric state reveals a restoration of collective proton-neutron mixed-symmetry structure near mid-shell. This provides the first explanation for the existence of pronounced collective mixed-symmetry structures in weakly-collective nuclei.Comment: 5 Pages, 3 figure

Shell-model studies on exotic nuclei around 132Sn

The study of exotic nuclei around 132Sn is a subject of current experimental and theoretical interest. Experimental information for nuclei in the vicinity of 132Sn, which have been long inaccessible to spectroscopic studies, is now available thanks to new advanced facilities and techniques. The experimental data which have been now become available for these neutron-rich nuclei may suggest a modification in the shell structure. They are, in fact, somewhat different from what one might expect by extrapolating the existing results for N<82, and as a possible explanation a change in the single-proton level scheme has been suggested. The latter would be caused by a more diffuse nuclear surface, and could be seen as a precursor of major effects which should show up at larger neutron excess. New data offer therefore the opportunity to test the shell model and look for a possible evolution of shell structure when going toward neutron drip line. This is stimulating shell-model studies in this region. Here, we present an overview of recent shell-model studies of 132Sn neighbors, focusing attention on those calculations employing realistic effective interactions.Comment: 8 pages, 4 tables, invited talk at INPC2007, Tokyo, Japan, June 3-8 2007. To be published in Nuclear Physics

Shell-model study of quadrupole collectivity in light tin isotopes

A realistic shell-model study is performed for neutron-deficient tin isotopes up to mass A=108. All shell-model ingredients, namely two-body matrix elements, single-particle energies, and effective charges for electric quadrupole transition operators, have been calculated by way of the many-body perturbation theory, starting from a low-momentum interaction derived from the high-precision CD-Bonn free nucleon-nucleon potential. The focus has been put on the enhanced quadrupole collectivity of these nuclei, which is testified by the observed large B(E2;0+ -> 2+)s. Our results evidence the crucial role played by the Z=50 cross-shell excitations that need to be taken into account explicitly to obtain a satisfactory theoretical description of light tin isotopes. We find also that a relevant contribution comes from the calculated neutron effective charges, whose magnitudes exceed the standard empirical values. An original double-step procedure has been introduced to reduce effectively the model space in order to overcome the computational problem.Comment: 6 pages, 6 figures, 2 table

Organizational Green IT: It seems the bottom line rules

As the perceived importance of environmental sustainability has grown, there has been increasing discussion on both reducing the environmental impact of IT and on increasing the role IS plays as a potential source of environmental solutions. An understanding of the factors that influence organizations towards green IT and IS may assist in both predicting future behavior and creating mechanisms to encourage more sustainable organizations. Using an online survey, this paper refines a model exploring the factors which influence the extent of green IT in organizations. Regression analysis revealed that the extent of green IT in organizations is influenced by a combination of the influence of management, bottom line considerations and normative legitimation pressures. The regression indicated a good fit for the developed model, providing a basis for further research

Spin gap behavior in Cu2_2Sc2_2Ge4_4O13_{13} by 45^{45}Sc nuclear magnetic resonance

We report the results of a $^{45}$Sc nuclear magnetic resonance (NMR) study on the quasi-one-dimensional compound Cu$_2$Sc$_2$Ge$_4$O$_{13}$ at temperatures between 4 and 300 K. This material has been a subject of current interest due to indications of spin gap behavior. The temperature-dependent NMR shift exhibits a character of low-dimensional magnetism with a negative broad maximum at $T_{max}$ $\simeq$ 170 K. Below $$, the NMR shifts and spin lattice relaxation rates clearly indicate activated responses, confirming the existence of a spin gap in Cu$_2$Sc$_2$Ge% $_4$O$_{13}$. The experimental NMR data can be well fitted to the spin dimer model, yielding a spin gap value of about 275 K which is close to the 25 meV peak found in the inelastic neutron scattering measurement. A detailed analysis further points out that the nearly isolated dimer picture is proper for the understanding of spin gap nature in Cu$_2$Sc$_2$Ge$_4$O$_{13}$.Comment: 4 pages, 6 figures, submitted to Phys. Rev.

Low-momentum Nucleon-Nucleon Potential and Hartree-Fock Calculations

A low-momentum nucleon-nucleon (NN) potential V-low-k is derived from modern realistic NN potentials by integrating out the high-momentum modes. The smooth V-low-k may be used as input for nuclear structure calculations instead of the usual Brueckner G matrix. Such an approach eliminates the energy dependence one finds in the G-matrix approach, allowing this interaction to be used directly in Hartree-Fock calculations. Bulk properties of 16O have been calculated starting from different NN potentials. Our results, obtained including up to second order contributions in the Goldstone expansion, are in good agreement with experiment.Comment: 7 pages, talk presented at IX Convegno su Problemi di Fisica Nucleare Teorica, Cortona (Italy), October 9-12 200

Shell-Model Calculations with Realistic Effective Interactions

In this paper, we present some results of shell-model calculations employing effective interactions derived from the CD-Bonn free nucleon-nucleon potential. These concern 18O, 134Te, and 210Po, and are part of a comprehensive study of nuclei around doubly closed shells. Comparison of the calculated results with experimental data illustrates the degree of accuracy of modern realistic shell-model calculations.Comment: Talk presented at INPC 2001, 29 July - 3 August 2001, Berkeley (USA