A hybrid approach to space power control

Conventional control systems have traditionally been utilized for space-based power designs. However, the use of expert systems is becoming important for NASA applications. Rocketdyne has been pursuing the development of expert systems to aid and enhance control designs of space-based power systems. The need for integrated expert systems is vital for the development of autonomous power systems

Completed cohomology of Shimura curves and a p-adic Jacquet-Langlands correspondence

We study indefinite quaternion algebras over totally real fields F, and give an example of a cohomological construction of p-adic Jacquet-Langlands functoriality using completed cohomology. We also study the (tame) levels of p-adic automorphic forms on these quaternion algebras and give an analogue of Mazur's `level lowering' principle.Comment: Updated version. Contains some minor corrections compared to the published versio

Influence of branch points in the complex plane on the transmission through double quantum dots

We consider single-channel transmission through a double quantum dot system consisting of two single dots that are connected by a wire and coupled each to one lead. The system is described in the framework of the S-matrix theory by using the effective Hamiltonian of the open quantum system. It consists of the Hamiltonian of the closed system (without attached leads) and a term that accounts for the coupling of the states via the continuum of propagating modes in the leads. This model allows to study the physical meaning of branch points in the complex plane. They are points of coalesced eigenvalues and separate the two scenarios with avoided level crossings and without any crossings in the complex plane. They influence strongly the features of transmission through double quantum dots.Comment: 30 pages, 14 figure

The equation of state of neutron star matter and the symmetry energy

We present an overview of microscopical calculations of the Equation of State (EOS) of neutron matter performed using Quantum Monte Carlo techniques. We focus to the role of the model of the three-neutron force in the high-density part of the EOS up to a few times the saturation density. We also discuss the interplay between the symmetry energy and the neutron star mass-radius relation. The combination of theoretical models of the EOS with recent neutron stars observations permits us to constrain the value of the symmetry energy and its slope. We show that astrophysical observations are starting to provide important insights into the properties of neutron star matter.Comment: 7 pages, 3 figure, talk given at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

Approaches to the Design of Biotechnical Streambank Stabilization: Volume I—A Guide to the Literature

Streambank stabilization has traditionally been performed with riprap for which reliable design and installation procedures are available. Due to concerns about the environmental impact of riprap, there has been increasing interest in more natural biotechnical (or bioengineering) alternatives. A review of the litera­ture on biotechnical approaches to streambank stabilization has been per­formed, with a focus on those works that might be particularly useful in developing design guidelines or standards for the Indiana Department of Transportation. Works that synthesized the literature (up to about the year 2000) and so covered a broad range of topics, were examined, including monographs and manuals published by federal and state agencies. More recent publications were also found on narrower more specific topics, including the ecological effects of riprap and bio­technical approaches, advances in the geotechnical modeling of vegetation effects on bank stability, the effectiveness of biotechnical measures, and screening methods for selecting appropriate measures. Implications of the reviewed work for the development of design guidelines are discussed

Approaches to the Design of Biotechnical Streambank Stabilization: Volume III—Design Guidelines

A conceptual framework for the design of biotechnical streambank revetment is proposed. It is intended to be simple in practice, flexible in being widely applicable, familiar in retaining cer­tain aspects of current practice while being patterned after other aspects, and encouraging a more environmentally sensitive approach to reliable streambank protection for INDOT projects. It distinguishes between a toe zone, where traditional hard armoring techniques such as those already included in the INDOT standard designs are more appropriate, and an upper bank zone where vegetation-based techniques would typically be applied. Default techniques are identified to simplify the choice of measures for \u27routine\u27 problems, but more case-specific techniques may also be selected. Primary techniques that offer immediate protection on their own are also distin­guished from supplementary techniques that are used only in combination with other (primary) techniques. The boundary between the toe zone and the upper bank zone is proposed to be the maximum of the ordinary high water mark (or bankfull elevation), the elevation corresponding to the 2-year discharge, and the elevation corresponding to the point that is one third up the slope from the bank toe at the design discharge (for streambank protection). For the upper bank zone, for bank slopes up to 2H:1V, regrading and revegetation with herbaceous species together with the use of rolled erosion control products (RECPs) is proposed as the default. The other (non-default) main primary technique for the upper bank zone is the vegetated mechanically stabilized earth (VMSE, or vegetated reinforced soil slope VRSS, or soil lifts) option (where revegetation with herbaceous species is also considered standard). This requires more engineering and construct­ion effort but is appropriate for those projects where a more vertical (up to maximum bank slope of 1H:1V) solution is desired. The supplementary techniques to be included are live staking to be used with the regrading option, and brush-layering to be used with the VMSE option

Approaches to the Design of Biotechnical Streambank Stabilization: Volume II—A Field Assessment

As part of a larger project to develop guidelines for the design of biotechnical approaches to streambank stabilization to be included in INDOT standard designs and specifications, a field assessment was undertaken of 26 sites, of which 13 were INDOT sites. Multiple techniques were frequently installed in combination, which resulted in 47 samples of 12 different techniques at the 26 sites. Each site was visited at least once and the measures were visually inspected for evi­dence of damage either to the measure or to the streambank being protected. Some of the field assessments were supplemented by interviews with designers involved in the INDOT projects; the general merits of biotechnical techniques were discussed together with those of specific tech­niques that might be included in a standard design. The assessment resulted in grouping the techniques into three broad categories: i) typically reliable techniques that could be used where tolerance for bank instability is very low, and generally involving hard armor, ii) potentially reliable techniques where the tolerance for bank instability is low to moderate, and iii) techniques that are appropriate only for special circumstances or to be used only in combination with measures from the other two groups

On the two-dimensional rotational body of maximal Newtonian resistance

We investigate, by means of computer simulations, shapes of nonconvex bodies that maximize resistance to their motion through a rarefied medium, considering that bodies are moving forward and at the same time slowly rotating. A two-dimensional geometric shape that confers to the body a resistance very close to the theoretical supremum value is obtained, improving previous results.Comment: This is a preprint version of the paper published in J. Math. Sci. (N. Y.), Vol. 161, no. 6, 2009, 811--819. DOI:10.1007/s10958-009-9602-

Critical strength of attractive central potentials

We obtain several sequences of necessary and sufficient conditions for the existence of bound states applicable to attractive (purely negative) central potentials. These conditions yields several sequences of upper and lower limits on the critical value, $g_{\rm{c}}^{(\ell)}$, of the coupling constant (strength), $g$, of the potential, $V(r)=-g v(r)$, for which a first $\ell$-wave bound state appears, which converges to the exact critical value.Comment: 18 page

Completeness of evanescent modes in layered dielectrics

In the presence of a dielectric slab, the modes of the free electromagnetic field comprise traveling modes, consisting of incoming, reflected, and transmitted parts, as well as trapped modes that are subject to repeated total internal reflection and emerge as evanescent field outside the slab. Traveling modes have a continuous range of frequencies, but trapped modes occur only at certain discrete frequencies. We solve the problem of which relative weight to use when summing over all modes, as commonly required in perturbative calculations. We demonstrate the correctness of our method by showing the completeness of electromagnetic field modes in the presence of a dielectric slab. We derive a convenient method of summing over all modes by means of a single contour integral, which is very useful in standard quantum electrodynamic calculations