Development of an advanced composite aileron for the L-1011 transport aircraft

Significant improvements in structural efficiency can be achieved by the utilization of advanced composites for construction of aircraft secondary structures. Careful evaluation of alternate designs and materials for the L-1011 advanced composite inboard aileron has led to the selection of several unique material combinations and easily manufactured structural configurations. The advanced composite aileron is a direct replacement for the metal aileron with a weight savings of 23 percent. Due to the configurational simplicity of the components within the composite aileron, and because it contains 50 percent fewer parts and fasteners than the metal aileron, it is predicted that the composite aileron will be cost competitive with the metal aileron in a production environment. Structural analysis of the composite aileron, in conjunction with the design data, concept verification, and ground tests, indicates that the composite aileron design meets or exceeds structural requirements

Advanced composite aileron for L-1011 transport aircraft: Design and analysis

Detail design of the composite aileron has been completed. The aileron design is a multi-rib configuration with single piece upper and lower covers mechanically fastened to the substructure. Covers, front, spar and ribs are fabricated with graphite/epoxy tape or fabric composite material. The design has a weight savings of 23 percent compared to the aluminum aileron. The composite aileron has 50 percent fewer fasteners and parts than the metal aileron and is predicted to be cost competitive. Structural integrity of the composite aileron was verified by structural analysis and an extensive test program. Static, failsafe, and vibration analyses have been conducted on the composite aileron using finite element models and specialized computer programs for composite material laminates. The fundamental behavior of the composite materials used in the aileron was determined by coupon tests for a variety of environmental conditions. Critical details of the design were interrogated by static and fatigue tests on full-scale subcomponents and subassemblies of the aileron

Advanced composite aileron for L-1011 transport aircraft, task 1

Structural design and maintainability criteria were established and used as a guideline for evaluating a variety of configurations and materials for each of the major subcomponents. From this array of subcomponent designs, several aileron assemblies were formulated and analyzed. The selected design is a multirib configuration with sheet skin covers mechanically fastened to channel section ribs and spars. Qualitative analysis of currently available composite material systems led to the selection of three candidate materials on which comparative structural tests were conducted to measure the effects of environment and impact damage on mechanical property retention. In addition, each system was evaluated for producibility characteristics. From these tests, Thornel 300/5208 unidirectional tape was selected for the front spar and covers, and Thornel 300 fabric/5208 was chosen for the ribs

Geological setting and petrochemistry of early Middle Devonian volcanic and gabbroic rocks in the Guysborough area, Nova Scotia

Mapping, petrological studies, and U-Pb dating of volcanic and plutonic units have provided a new understanding of the stratigraphy and paleotectonic setting of rocks in the Guysborough area. From base to top, the stratigraphic sequence is interpreted to consist of: (1) volcanic flows and pyroclastic rocks, with minor interlayered sedimentary rocks (Sunnyville Formation), (2) varied conglomerate (Glenkeen Formation), (3) quartz wacke with minor interlayered quartz arenite and conglomerate, and (4) massive to shaly or laminated siltstone. These volcanic and sedimentary units arc intruded by small gabbroic plutons, sills, and dykes. All the units are early Middle Devonian, based on a U-Pb (zircon) age of 389 ± 2 Ma for rhyolitic tuff from the Sunnyville Formation, and a preliminary U-Pb (baddelcyite) age of ca. 38S Ma for one of the gabbroic plutons in the siltstone unit. Based on whole-rock chemistry, the mafic volcanic and gabbroic rocks are similar, and formed in a continental within-plate setting. However, the rocks in the eastern part of the map area are more alkalic than those in the west, which are dominantly tholeiitic. The mafic magmas are interpreted to have formed by partial melting of the subcontinental upper mantle and to have evolved by crystal fractionation processes; the more alkalic magmas in the east may represent lesser amounts of partial melting in that area. This interpretation is consistent with the presence of felsic volcanic rocks only in the western part of the area. They may represent crustal melts formed as a result of mafic magma underplating of the crust. The regional tectonic significance of these igneous rocks is not yet resolved, but they are clearly older than Late Devonian to Carboniferous igneous units elsewhere in northern mainland Nova Scotia and in Cape Breton Island with which they were previously assumed to be correlative. RÉSUMÉ Des travaux de cartographic, des études pétrologiques et la datation au U-Pb d'unités volcaniques et plutoniques ont permis une meilleure compréhension de la stratigraphic et du cadre paléotcctonique des roches du secteur de Guysborough. On interprèts la composition de la séquence stratigraphique comme suit, de sa base à son sommet : 1) des écoulements volcaniques et des roches pyroclastiques, avec une proportion mineure de roches sédimentaires intercalécs (Formation Sunnyville); 2) un conglomerat diversify (Formation Glenkeen); 3) de la wacke qurtzeuse avec une présence mineure de conglomerat et de quartzite sédimentaire interstratifies; et 4) des siltstones massifs à schistcux ou feuilletés. Ces unités volcaniques et sédimentaires sont pénétries par de petits dykes, filons-couches et plutons gabbrolques. Toutes les unités remontent au début du Dévonien moyen d'apres une datation au U-Pb (zircon) situant a 389+2 Ma le tuf rhyolitique de la Formation Sunnyville ainsi qu'une datation au U-Pb (baddeleyite) situant provisoirement l'un des plutons gabbrolques de l'unité de siltstones a environ 38S Ma. D'après la chimie des roches, les roches volcanomaflques et gabbrolques sont semblabes et elles se sont formées dans un cadre intra-plaque continental. Les roches de la partie orientate du secteur cartographique sont cependant plus alcalines que celles de l'ouest, en predominance tholéeiitiques. Selon l'interprétation avancée, les magmas mafiques se seraient formes par suite d'une fonte partielle du manteau sous-continental supérieur et ils auraient évolué au moyen de processus de différenciation magmatique; les magmas plus alcalins de l'est pourraient représentor une fonte partielle moins importante dans ce secteur. Cette interprétation est compatible avec la présence de roches volcano-felsiques limitée a la partie ouest du secteur. Elles pourraient représentor des éléments crustaux fondus formés par suite d'une remontée de magma mafique sous les plaques de la croûte. On n'a pas encore déterminé ('importance tectonique régionale dc ces roches ignées, mais elles sont clairement plus anciennes que les unités ignées du Dévonien supérieur au Carbonifère des autres régions de L'intérieur de la Nouvelle-Écosse et de l'ile du Cap-Breton avec lesquelles on les supposait auparavant corrélatives. [Traduit par la rédaction

Cost effective, experimentally robust differential-expression analysis for human/mammalian, pathogen and dual-species transcriptomics.

As sequencing read length has increased, researchers have quickly adopted longer reads for their experiments. Here, we examine 14 pathogen or host-pathogen differential gene expression data sets to assess whether using longer reads is warranted. A variety of data sets was used to assess what genomic attributes might affect the outcome of differential gene expression analysis including: gene density, operons, gene length, number of introns/exons and intron length. No genome attribute was found to influence the data in principal components analysis, hierarchical clustering with bootstrap support, or regression analyses of pairwise comparisons that were undertaken on the same reads, looking at all combinations of paired and unpaired reads trimmed to 36, 54, 72 and 101 bp. Read pairing had the greatest effect when there was little variation in the samples from different conditions or in their replicates (e.g. little differential gene expression). But overall, 54 and 72 bp reads were typically most similar. Given differences in costs and mapping percentages, we recommend 54 bp reads for organisms with no or few introns and 72 bp reads for all others. In a third of the data sets, read pairing had absolutely no effect, despite paired reads having twice as much data. Therefore, single-end reads seem robust for differential-expression analyses, but in eukaryotes paired-end reads are likely desired to analyse splice variants and should be preferred for data sets that are acquired with the intent to be community resources that might be used in secondary data analyses

Scattering in the PT-symmetric Coulomb potential

Scattering on the ${\cal PT}$-symmetric Coulomb potential is studied along a U-shaped trajectory circumventing the origin in the complex $x$ plane from below. This trajectory reflects ${\cal PT}$ symmetry, sets the appropriate boundary conditions for bound states and also allows the restoration of the correct sign of the energy eigenvalues. Scattering states are composed from the two linearly independent solutions valid for non-integer values of the 2L parameter, which would correspond to the angular momentum in the usual Hermitian setting. Transmission and reflection coefficients are written in closed analytic form and it is shown that similarly to other ${\cal PT}$-symmetric scattering systems the latter exhibit handedness effect. Bound-state energies are recovered from the poles of the transmission coefficients.Comment: Journal of Physics A: Mathematical and Theoretical 42 (2009) to appea

Creation of Rydberg Polarons in a Bose Gas

We report spectroscopic observation of Rydberg polarons in an atomic Bose gas. Polarons are created by excitation of Rydberg atoms as impurities in a strontium Bose-Einstein condensate. They are distinguished from previously studied polarons by macroscopic occupation of bound molecular states that arise from scattering of the weakly bound Rydberg electron from ground-state atoms. The absence of a $p$-wave resonance in the low-energy electron-atom scattering in Sr introduces a universal behavior in the Rydberg spectral lineshape and in scaling of the spectral width (narrowing) with the Rydberg principal quantum number, $n$. Spectral features are described with a functional determinant approach (FDA) that solves an extended Fr\"{o}hlich Hamiltonian for a mobile impurity in a Bose gas. Excited states of polyatomic Rydberg molecules (trimers, tetrameters, and pentamers) are experimentally resolved and accurately reproduced with FDA.Comment: 5 pages, 3 figure

Theory of excitation of Rydberg polarons in an atomic quantum gas

We present a quantum many-body description of the excitation spectrum of Rydberg polarons in a Bose gas. The many-body Hamiltonian is solved with functional determinant theory, and we extend this technique to describe Rydberg polarons of finite mass. Mean-field and classical descriptions of the spectrum are derived as approximations of the many-body theory. The various approaches are applied to experimental observations of polarons created by excitation of Rydberg atoms in a strontium Bose-Einstein condensate.Comment: 14 pages, 9 figures. arXiv admin note: substantial text overlap with arXiv:1706.0371

Identification of observables in quantum toboggans

Quantum systems with real energies generated by an apparently non-Hermitian Hamiltonian may re-acquire the consistent probabilistic interpretation via an ad hoc metric which specifies the set of observables in the updated Hilbert space of states. The recipe is extended here to quantum toboggans. In the first step the tobogganic integration path is rectified and the Schroedinger equation is given the generalized eigenvalue-problem form. In the second step the general double-series representation of the eligible metric operators is derived.Comment: 25 p

Phase transitions with finite atom number in the Dicke Model

Two-level atoms interacting with a one mode cavity field at zero temperature have order parameters which reflect the presence of a quantum phase transition at a critical value of the atom-cavity coupling strength. Two popular examples are the number of photons inside the cavity and the number of excited atoms. Coherent states provide a mean field description, which becomes exact in the thermodynamic limit. Employing symmetry adapted (SA) SU(2) coherent states (SACS) the critical behavior can be described for a finite number of atoms. A variation after projection treatment, involving a numerical minimization of the SA energy surface, associates the finite number phase transition with a discontinuity in the order parameters, which originates from a competition between two local minima in the SA energy surface.Comment: 8 pages, 10 figures, Conference Proceedings of CEWQO-2012, to be published as a Topical Issue of the journal Physica Script