Flutter parametric studies of cantilevered twin-engine transport type wing with and without winglet. Volume 2: Transonic and density effect investigations

Flutter characteristics of a cantilevered high aspect ratio wing with winglet were investigated. The configuration represented a current technology, twin engine airplane. Compressibility effects through transonic Mach numbers and a wide range of mass-density ratios were evaluated on a low speed and high speed model. Four flutter mechanisms were obtained from test, and analysis from various combinations of configuration parameters. It is shown that the coupling between wing tip vertical and chordwise motions have significant effect under some conditions. It is concluded that for the flutter model configurations studied, the winglet related flutter is amenable to the conventional flutter analysis techniques. The low speed model flutter and the high-speed model flutter results are described

Search for resonances in positron-atom systems

No one likes to see a scattering cross section curve that is too smooth; it is much more interesting to find bumps and wiggles and most interesting if it is possible to understand their cause. Several types of resonances were clearly established in positron-containing systems: those lying just below a degenerate threshold (like 2s-2p in hydrogenic atoms or ions) and those representing Coulomb bound states in a rearranged channel (like Ps + H reversing positron +H(-)). Recently, two new sorts of resonances have been reported for which the resonant mechanism is not clear. The first is a very low lying resonance in the e-Ps system (obtained by an adiabatic expansion method), and the second is a similarly low lying two channel resonance in the positron -H system (obtained by a close-coupling technique.) These developments encouraged the examination of such systems using the standard methods of stabilization and complex rotation. Most of the results are negative; the low lying resonances in either system are verified. Some indication of new resonances in the e(+)-He(+) system is found; this may be caused by the attraction between Ps in the n=2 state and the He(++) nucleus

Effects of winglet on transonic flutter characteristics of a cantilevered twin-engine-transport wing model

A transonic model and a low-speed model were flutter tested in the Langley Transonic Dynamics Tunnel at Mach numbers up to 0.90. Transonic flutter boundaries were measured for 10 different model configurations, which included variations in wing fuel, nacelle pylon stiffness, and wingtip configuration. The winglet effects were evaluated by testing the transonic model, having a specific wing fuel and nacelle pylon stiffness, with each of three wingtips, a nonimal tip, a winglet, and a nominal tip ballasted to simulate the winglet mass. The addition of the winglet substantially reduced the flutter speed of the wing at transonic Mach numbers. The winglet effect was configuration-dependent and was primarily due to winglet aerodynamics rather than mass. Flutter analyses using modified strip-theory aerodynamics (experimentally weighted) correlated reasonably well with test results. The four transonic flutter mechanisms predicted by analysis were obtained experimentally. The analysis satisfactorily predicted the mass-density-ratio effects on subsonic flutter obtained using the low-speed model. Additional analyses were made to determine the flutter sensitivity to several parameters at transonic speeds

Radiative transitions involving the (2p2)(3 Pe) metastable autodetaching of H(-)

The absorption coefficient for the free-bound transition H (ls) + e(-)+ h omega yields H(-)(2 sq p,(3)P(e)) is calculated (together with the differential emission rate for the inverse process) using ls - 2s - 2p close coupling continuum wave functions and a Hylleraas bound state wave function. A maximum in the absorption and emission spectra is found to occur at a photon wavelength of 1219.5 A, which is 2 A closer to the Lyman alpha line than predicted by the calculations of Drake, and is in closer agreement with the stellar absorption feature identified by Heap and Stecher. The free-bound absorption process appears to be a significant source of continuous ultraviolet opacity

Hybrid Theory of Electron-Hydrogenic Systems Elastic Scattering

Accurate electron-hydrogen and electron-hydrogenic cross sections are required to interpret fusion experiments, laboratory plasma physics and properties of the solar and astrophysical plasmas. We have developed a method in which the short-range and long-range correlations can be included at the same time in the scattering equations. The phase shifts have rigorous lower bounds and the scattering lengths have rigorous upper bounds. The phase shifts in the resonance region can be used to calculate very accurately the resonance parameters

Interactions of Positrons and Electrons with Hydrogenic Systems, Excitation, Resonances, and Photoabsorption in Two-Electron Systems

There are a number of approaches to study interactions of positrons and electrons with hydrogenic targets. Among the most commonly used are the method of polarized orbital, the close-coupling approximation, and the R-matrix formulation. The last two approaches take into account the short-range and long-range correlations. The method of polarized orbital takes into account only long-range correlations but is not variationally correct. This method has recently been modified to take into account both types of correlations and is variationally correct. It has been applied to calculate phase shifts of scattering from hydrogenic systems like H, He+, and Li2+. The phase shifts obtained using this method have lower bounds to the exact phase shifts and agree with those obtained using other approaches. This approach has also been applied to calculate resonance parameters in two-electron systems obtaining results which agree with those obtained using the Feshbach projection-operator formalism. Furthermore this method has been employed to calculate photodetachment and photoionization of two-electron systems, obtaining very accurate cross sections which agree with the experimental results. Photodetachment cross sections are particularly useful in the study of the opacity of the sun. Recently, excitation of the atomic hydrogen by electron impact and also by positron impact has been studied by this method

Accessibility of discoursal data in critical genre analysis: international commercial arbitration practice

A análise crítica de gênero, especialmente quando enfoca práticas profissionais específicas, depende de modo crucial da disponibilidade de dados discursivos da prática profissional sob investigação, o que nem sempre é fácil. Neste artigo abordo um exemplo típico desse tipo de dificuldade, enquanto enfoco uma iniciativa internacional em que estive envolvido nestes últimos anos, com a colaboração de mais de vinte equipes de pesquisa de um mesmo número de países. Ao nos debruçarmos sobre dados discursivos (narrativos, documentais e interacionais), é possível enxergar as motivações para processos e procedimentos interdiscursivos. Entretanto, o assim chamado dever de estrita confidencialidade, observado e praticado nas práticas de arbitragem internacional, torna difícil o acesso aos dados das práticas de arbitragem e, assim, de levar adiante uma pesquisa interdisciplinar crítica com base na noção de gênero. No presente artigo enfocarei algumas das questões importantes envolvidas no estudo da prática profissional e discutirei as implicações desse requisito de confidencialidade amplamente obedecido, bem como suas implicações para a pesquisa na e desenvolvimento da instituição de arbitragem. Também proponho alternativas para a coleta de dados da prática de arbitragem, de modo a tornar esse tipo de pesquisa possível.El análisis crítico de género, especialmente cuando enfoca prácticas profesionales específicas, depende de modo crucial de la disponibilidad de datos discursivos de la práctica profesional bajo investigación, lo que ni siempre es fácil. En este artículo abordo un ejemplo típico de ese tipo de dificultad, mientras enfoco una iniciativa internacional en la que estuve envuelto en estos últimos varios años, con la colaboración de más de veinte equipos de investigación de un mismo número de países. Al inclinarnos sobre datos discursivos (narrativos, documentales e interacionales), es posible ver las motivaciones para procesos y procedimientos interdiscursivos. Al mismo tiempo, el así llamado deber de estricta confidencialidad, observado y practicado en las prácticas de arbitraje internacional, vuelven difícil el acceso a los datos de las prácticas de arbitraje y, así, de llevar adelante una investigación interdisciplinar crítica con base en la noción de género. En el presente artículo enfocaré algunas de las cuestiones importantes involucradas en el estudio de la práctica profesional y discutiré las implicaciones de ese requerimiento de confidencialidad ampliamente obedecido, bien como sus implicancias para la pesquisa en el desarrollo de la institución de arbitraje. También propongo alternativas para la colecta de datos de la práctica de arbitraje, de modo a tornar ese tipo de investigación posible.Critical genre analysis, especially targeting specific professional practices, crucially depends on the availability of discursive data from the professional practice under investigation, which is not always easily accessible. In this paper, I take up a typical example of this kind of difficulty focusing on an international initiative, in which I have been involved for the last several years, with collaboration from more than twenty research teams from as many countries. By drawing on discoursal data (narrative, documentary and interactional), it is possible to look at the motivations for interdiscursive processes and procedures. However, the so-called duty to strict confidentiality observed and practiced in international arbitration practice makes it difficult to get access to data from arbitration practice and thus to undertake such critical genre-based interdisciplinary research. In this paper, I will focus on some of the important issues involved in this study of professional practice and discuss implications of this generally assumed requirement of confidentiality, and its implications for research in and development of the institution of arbitration. I also propose alternatives to collection of data from arbitration practice to make such research possible

Forensic Linguist Tej Bhatia on the Hunt for the Unabomber

From article: [Editor’s note: Discovery Channel’s new 8-part series MANHUNT: UNABOMBER is about the FBI investigator Jim Fitzgerald who identified the Unabomber as Ted Kaczynski based on his writings–pioneering the use of what is now called forensic linguistics. The series stars Sam Worthington and Paul Bettany, and also features Chris Noth, Elizabeth Reaser, and Brian F. O’Byrne. Science & Film commissioned Syracuse University linguistics professor Dr. Tej Bhatia to write about the case. The series is available via Netflix and Amazon.

The dissolution of magnesium in strong acids

The rapidly growing demand for magnesium and magnesium-base alloys in the manufacture of aircraft has led to a great amount of research into the corrosion characteristics of these materials. The result of such research has been the development of suitable magnesium alloys and protective coatings to retard corrosion. The standard electrode potential of magnesium lies between -2.35 volts and -2.54 volts at 25⁰C (hydrogen scale). Thus, magnesium lies next to aluminium in the electrochemical series of elements. The atmospheric corrosion of magnesium has been studied under conditions of indoor and outdoor exposure. Under these conditions the initial attack is formation of a hydroxide film which has a tendency to absorb carbon dioxide and moisture from the air. As a pure metal, magnesium is attacked rapidly by hydrochloric, perchloric, sulfuric, and nitric acids. In hydrofluoric acid the metal does not corrode at an appreciable rate. Magnesium metal is rarely, if ever, used in unalloyed conditions for structural purposes. The corrosion rate is retarded by alloying the metal with small quantities of aluminium, manganese, and zinc. The purpose of this present investigation was to study the dissolution of magnesium in strong acids. It was also aimed to investigate whether magnesium metal exhibits uncommon valence characteristics as reported in the literature. The strong acids included hydrochloric, perchloric, and sulfuric acids --Introduction, pages 1-2