Comparison of aerodynamic noise from three nose-cylinder combinations

Results of experiments with three different cylinder and blunted nose combinations are discussed. Combinations include smooth cylinder with single 15 deg cone, smooth cylinder with double cone of 25 and 10 deg, and longitudinally corrugated cylinder with similar double cone

On minimal Ramsey graphs and Ramsey equivalence in multiple colours

For an integer $q\ge 2$, a graph $G$ is called $q$-Ramsey for a graph $H$ if every $q$-colouring of the edges of $G$ contains a monochromatic copy of $H$. If $G$ is $q$-Ramsey for $H$, yet no proper subgraph of $G$ has this property then $G$ is called $q$-Ramsey-minimal for $H$. Generalising a statement by Burr, Ne\v{s}et\v{r}il and R\"odl from 1977 we prove that, for $q\ge 3$, if $G$ is a graph that is not $q$-Ramsey for some graph $H$ then $G$ is contained as an induced subgraph in an infinite number of $q$-Ramsey-minimal graphs for $H$, as long as $H$ is $3$-connected or isomorphic to the triangle. For such $H$, the following are some consequences. (1) For $2\le r< q$, every $r$-Ramsey-minimal graph for $H$ is contained as an induced subgraph in an infinite number of $q$-Ramsey-minimal graphs for $H$. (2) For every $q\ge 3$, there are $q$-Ramsey-minimal graphs for $H$ of arbitrarily large maximum degree, genus, and chromatic number. (3) The collection $\{{\cal M}_q(H) : H \text{ is 3-connected or } K_3\}$ forms an antichain with respect to the subset relation, where ${\cal M}_q(H)$ denotes the set of all graphs that are $q$-Ramsey-minimal for $H$. We also address the question which pairs of graphs satisfy ${\cal M}_q(H_1)={\cal M}_q(H_2)$, in which case $H_1$ and $H_2$ are called $q$-equivalent. We show that two graphs $H_1$ and $H_2$ are $q$-equivalent for even $q$ if they are $2$-equivalent, and that in general $q$-equivalence for some $q\ge 3$ does not necessarily imply $2$-equivalence. Finally we indicate that for connected graphs this implication may hold: Results by Ne\v{s}et\v{r}il and R\"odl and by Fox, Grinshpun, Liebenau, Person and Szab\'o imply that the complete graph is not $2$-equivalent to any other connected graph. We prove that this is the case for an arbitrary number of colours

\u3ci\u3eTiphia Vernalis\u3c/i\u3e (Hymenoptera: Tiphiidae) Parasitizing Oriental Beetle, \u3ci\u3eAnomala Orientalis\u3c/i\u3e (Coleoptera: Scarabaeidae) in a Nursery

(excerpt) Tiphia vernalis Rohwer is native to China, Japan, and Korea where it is an external parasite of Popillia spp. (King 1931). It was released into the United States from China and Korea during the mid-1920s through early 30s (Fleming 1968). After it became established in the United States, releases were made from domestic sources beginning in 1931 (King et al. 1951). Tiphia vernalis was released into Ohio sporadically during 1936-1953 (King et al.1951). Tiphia vernalis has been reported parasitizing Popillia spp. (P. quadriguttata (Fabricius) in Korea; P. chinensis (Frivaldsky) and P. formosana (Arrow) in China; and P. japonica Newman in Japan) exclusively in the field (Balock 1934, Fleming 1968). It accepted Anomala (=Exomala) orientalis Waterhouse (oriental beetle) as a host in the laboratory and cocoons were obtained (King et al.1927, Balock 1934), but there are no previously published reports of T. vernalis parasitizing A. orientalis in the field

Unsteady airfoil stall

Dynamic and static stall data in relation to airfoil stall at subsonic speed

Unsteady aerodynamic analysis of space shuttle vehicles. Part 1: Summary report

An analysis of the unsteady aerodynamics of space shuttle vehicles was performed. The results show that slender wing theory can be modified to give the potential flow static and dynamic characteristics over a large Mach number range from M = 0 to M 1. A semi-empirical analytic approximation is derived for the loads induced by the leading edge vortex; and it is shown that the developed analytic technique gives good prediction of experimentally determined steady and unsteady delta wing aerodynamics, including the effects of leading edge roundness. At supersonic speeds, attached leading edge flow is established and shock-induced flow separation effects become of concern. Analysis of experimental results for a variety of boost configurations led to a definition of the main features of the flow interference effects between orbiter (delta wing) and booster. The effects of control deflection on the unsteady aerodynamics of the delta-wing orbiter were also evaluated

Unsteady airfoil stall and stall flutter

Unsteady airfoil stall characteristics using static data input for predicting stall flutter boundaries of space shuttle win

Unsteady aerodynamic analysis of space shuttle vehicles. Part 4: Effect of control deflections on orbiter unsteady aerodynamics

The unsteady aerodynamics of the 040A orbiter have been explored experimentally. The results substantiate earlier predictions of the unsteady flow boundaries for a 60 deg swept delta wing at zero yaw and with no controls deflected. The test revealed a previously unknown region of discontinuous yaw characteristics at transonic speeds. Oilflow results indicate that this is the result of a coupling between wing and fuselage flows via the separated region forward of the deflected elevon. In fact, the large leeward elevon deflections are shown to produce a multitude of nonlinear stability effects which sometimes involve hysteresis. Predictions of the unsteady flow boundaries are made for the current orbiter. They should carry a good degree of confidence due to the present substantiation of previous predictions for the 040A. It is proposed that the present experiments be extended to the current configuration to define control-induced effects. Every effort should be made to account for Reynolds number, roughness, and possible hot-wall effects on any future experiments

Do Foreign Exchange Markets Matter Dor Industry Stock Returns ? An empirical investigation

In this paper, we develop a bivariate two factor-two country GARCH model of stock returns in order to investigate whether exchange rate fluctuations have a significant impact on the conditional mean, variance, and correlation of industry stock returns. Weekly data for seven industries in five European countries over the 1990-1998 period are used. We document that exchange rates have a significant effect on expected industry stock returns and on their volatility. The magnitude of this effect is, however, quite small. The contribution of the exchange rate factor to the time-varying correlation coefficients between two countries’industry returns is also very modest. The paper also shows that the importance of the exchange rate spillovers is influenced by the exchange rate regime, the magnitude and the direction of exchange rate shocks.Industry stock returns; Fx market; Volatility; International correlation