ALESEP: A computer program for the analysis of airfoil leading edge separation bubbles

The ALESEP program for the analysis of the inviscid/viscous interaction which occurs due to the presence of a closed laminar transitional separation bubble on an airflow is presented. The ALESEP code provides a iterative solution of the boundary layer equations expressed in an inverse formulation coupled to a Cauchy integral representation of the inviscid flow. This interaction analysis is treated as a local perturbation to a known solution obtained from a global airfoil analysis. Part of the required input to the ALESEP code are the reference displacement thickness and tangential velocity distributions. Special windward differencing may be used in the reversed flow regions of the separation bubble to accurately account for the flow direction in the discretization of the streamwise convection of momentum. The ALESEP code contains a forced transition model based on a streamwise intermittency function and a natural transition model based on a solution of the integral form of the turbulent kinetic energy equation. Instructions for the input/output, and program usage are presented

Pressures measured in flight on the aft fuselage and external nozzle of a twin-jet fighter

Fuselage, boundary layer, and nozzle pressures were measured in flight for a twin jet fighter over a Mach number range from 0.60 to 2.00 at test altitudes of 6100, 10,700, and 13,700 meters for angles of attack ranging from 0 deg to 7 deg. Test data were analyzed to find the effects of the propulsion system geometry. The flight variables, and flow interference. The aft fuselage flow field was complex and showed the influence of the vertical tail, nacelle contour, and the wing. Changes in the boattail angle of either engine affected upper fuselage and lower fuselage pressure coefficients upstream of the nozzle. Boundary layer profiles at the forward and aft locations on the upper nacelles were relatively insensitive to Mach number and altitude. Boundary layer thickness decreased at both stations as angle of attack increased above 4 deg. Nozzle pressure coefficient was influenced by the vertical tail, horizontal tail boom, and nozzle interfairing; the last two tended to separate flow over the top of the nozzle from flow over the bottom of the nozzle. The left nozzle axial force coefficient was most affected by Mach number and left nozzle boattail angle. At Mach 0.90, the nozzle axial force coefficient was 0.0013

Press discourses on ecological crises in the UK, Israel, and Hungary

This article explores the relationships between political projects of belonging and approaches to environmental and climate ecological crises via comparing centre-right and centre-left newspapers in the UK, Israel and Hungary. Our theoretical framework draws on Nira Yuval-Davis's work on the politics of belonging as a way of understanding and framing the different political projects that accompany reporting on ecological issues. Focusing on selected national and international case studies on these issues at the centre of public debate during the last two decades, the paper explores and compares these relationships by examining the eco-relational, spatial, temporal and normative framing dimensions of the political projects of belonging as expressed in these articles. The findings of the analysis show that, despite different cultural and historical contexts, the most significant dividing line is not among countries but between the different political projects of belonging of the newspapers. This can be seen even when dealing with country-specific, rather than international, case studies. Overall, centre-right newspapers tend to focus on narrow nationalist interests concerning the climate crisis and do not produce discourses of urgency to resolve the crisis except when reporting on major international political agendas. They are also more inclined to focus on the economic aspects of such efforts and how they would affect the “people”. The centre-left press, on the other hand, tends to prioritise ecological issues much more; it has wider global and planetary interdependent constructions of belonging and engages in the production of discourses of urgency in an attempt to solve the crisis and avoid future catastrophes. However, even in the centre-left press, especially in the UK, a tendency to remain within a western-centric perspective was observed

Effects of temperature upon the collapse of a Bose-Einstein condensate in a gas with attractive interactions

We present a study of the effects of temperature upon the excitation frequencies of a Bose-Einstein condensate formed within a dilute gas with a weak attractive effective interaction between the atoms. We use the self-consistent Hartree-Fock Bogoliubov treatment within the Popov approximation and compare our results to previous zero temperature and Hartree-Fock calculations The metastability of the condensate is monitored by means of the $l=0$ excitation frequency. As the number of atoms in the condensate is increased, with $T$ held constant, this frequency goes to zero, signalling a phase transition to a dense collapsed state. The critical number for collapse is found to decrease as a function of temperature, the rate of decrease being greater than that obtained in previous Hartree-Fock calculations.Comment: 4 pages LaTeX, 3 eps figures. To appear as a letter in J. Phys.

The use of Levy-Lees variables in three-dimensional boundary-layer flows

A method for solving a general class of three-dimensional boundary layer flows is developed. In the development, Levy-Lees variables are extended to three dimensions and equations are placed in these similarity variables. An implicit finite difference scheme which is stable for negative transverse velocities is used to solve these equations. The method developed is applied to obtain solutions for sharp and spherically blunted circular cones at angle of attack. Longitudinal and transverse distributions are presented for these cases. Good agreement is found with the results obtained by other numerical schemes and the experimental data of Tracy, for sharp circular cones at angle of attack. For spherically blunted cones at angle of attack, the results are in good agreement with axisymmetric sphere results up to the region where spherical symmetry holds

Do Solar Neutrino Experiments Imply New Physics?

None of the 1000 solar models in a full Monte Carlo simulation is consistent with the results of the chlorine or the Kamiokande experiments. Even if the solar models are forced artifically to have a \b8 neutrino flux in agreeement with the Kamiokande experiment, none of the fudged models agrees with the chlorine observations. The GALLEX and SAGE experiments, which currently have large statistical uncertainties, differ from the predictions of the standard solar model by $2 \sigma$ and $3 \sigma$, respectively.Comment: 7 pages (figures not included), Institute for Advanced Study number AST 92/51. For a hard copy with the figures, write: [email protected]

Measurement of the solar neutrino capture rate with gallium metal

The solar neutrino capture rate measured by the Russian-American Gallium Experiment (SAGE) on metallic gallium during the period January 1990 through December 1997 is 67.2 (+7.2-7.0) (+3.5-3.0) SNU, where the uncertainties are statistical and systematic, respectively. This represents only about half of the predicted Standard Solar Model rate of 129 SNU. All the experimental procedures, including extraction of germanium from gallium, counting of 71Ge, and data analysis are discussed in detail.Comment: 34 pages including 14 figures, Revtex, slightly shortene

Exact Results on the Space of Vacua of Four Dimensional SUSY Gauge Theories

We consider four dimensional quantum field theories which have a continuous manifold of inequivalent exact ground states -- a moduli space of vacua. Classically, the singular points on the moduli space are associated with extra massless particles. Quantum mechanically these singularities can be smoothed out. Alternatively, new massless states appear there. These may be the elementary massless particles or new massless bound states.Comment: 19 pages, RU-94-1

Multiple Current States of Two Phase-Coupled Superconducting Rings

The states of two phase-coupled superconducting rings have been investigated. Multiple current states have been revealed in the dependence of the critical current on the magnetic field. The performed calculations of the critical currents and energy states in a magnetic field have made it possible to interpret the experiment as the measurement of energy states into which the system comes with different probabilities because of the equilibrium and non-equilibrium noises upon the transition from the resistive state to the superconducting state during the measurement of the critical currentComment: 5 pages, 5 figure

On the Hardness of SAT with Community Structure

Recent attempts to explain the effectiveness of Boolean satisfiability (SAT) solvers based on conflict-driven clause learning (CDCL) on large industrial benchmarks have focused on the concept of community structure. Specifically, industrial benchmarks have been empirically found to have good community structure, and experiments seem to show a correlation between such structure and the efficiency of CDCL. However, in this paper we establish hardness results suggesting that community structure is not sufficient to explain the success of CDCL in practice. First, we formally characterize a property shared by a wide class of metrics capturing community structure, including "modularity". Next, we show that the SAT instances with good community structure according to any metric with this property are still NP-hard. Finally, we study a class of random instances generated from the "pseudo-industrial" community attachment model of Gir\'aldez-Cru and Levy. We prove that, with high probability, instances from this model that have relatively few communities but are still highly modular require exponentially long resolution proofs and so are hard for CDCL. We also present experimental evidence that our result continues to hold for instances with many more communities. This indicates that actual industrial instances easily solved by CDCL may have some other relevant structure not captured by the community attachment model.Comment: 23 pages. Full version of a SAT 2016 pape