Forward acoustic performance of a model turbofan designed for a high specific flow (QF-14)

Forward noise and overall aerodynamic performance are presented for a high-tip-speed fan having an exceptionally high average axial Mach number at the rotor inlet. This high Mach number is intended to attenuate forward noise at both the design-speed takeoff point, and at the unconventional low-pressure-ratio, design-speed approach point. As speed was increased near design, all forward noise components were reduced, and rear noise in the discharge duct was increased, indicating that the high Mach number flow at the rotor face is attenuating forward noise at takeoff. The fan at takeoff is some 5.5 to 11 dB quieter than several reference fans. Data at the point closest to approach indicated tentatively that the design-speed approach mode was 3 dB quieter than the conventional mode

Analytical study of hydrogen turbopump cycles for advanced nuclear rockets Progress report, Sep. 15, 1964 - Sep. 15, 1965

Hydrogen turbopump cycles for obtaining high engine inlet pressures in advanced nuclear rockets, and data on gaseous nuclear reactors and heavy gas containmen

Anti-pheromone as a tool for better exploration of search space

Many animals use chemical substances known as pheromones to induce behavioural changes in other members of the same species. The use of pheromones by ants in particular has lead to the development of a number of computational analogues of ant colony behaviour including Ant Colony Optimisation. Although many animals use a range of pheromones in their communication, ant algorithms have typically focused on the use of just one, a substance that encourages succeeding generations of (artificial) ants to follow the same path as previous generations. Ant algorithms for multi-objective optimisation and those employing multiple colonies have made use of more than one pheromone, but the interactions between these different pheromones are largely simple extensions of single criterion, single colony ant algorithms. This paper investigates an alternative form of interaction between normal pheromone and anti-pheromone. Three variations of Ant Colony System that apply the anti-pheromone concept in different ways are described and tested against benchmark travelling salesman problems. The results indicate that the use of anti-pheromone can lead to improved performance. However, if anti-pheromone is allowed too great an influence on ants' decisions, poorer performance may result

Mesoscale simulations of surfactant dissolution and mesophase formation

The evolution of the contact zone between pure surfactant and solvent has been studied by mesoscale simulation. It is found that mesophase formation becomes diffusion controlled and follows the equilibrium phase diagram adiabatically almost as soon as individual mesophases can be identified, corresponding to times in real systems of order 10 microseconds.Comment: 4 pages, 2 figures, ReVTeX

EIT: Solar corona synoptic observations from SOHO with an Extreme-ultraviolet Imaging Telescope

The Extreme-ultraviolet Imaging Telescope (EIT) of SOHO (solar and heliospheric observatory) will provide full disk images in emission lines formed at temperatures that map solar structures ranging from the chromospheric network to the hot magnetically confined plasma in the corona. Images in four narrow bandpasses will be obtained using normal incidence multilayered optics deposited on quadrants of a Ritchey-Chretien telescope. The EIT is capable of providing a uniform one arc second resolution over its entire 50 by 50 arc min field of view. Data from the EIT will be extremely valuable for identifying and interpreting the spatial and temperature fine structures of the solar atmosphere. Temporal analysis will provide information on the stability of these structures and identify dynamical processes. EIT images, issued daily, will provide the global corona context for aid in unifying the investigations and in forming the observing plans for SOHO coronal instruments

NEW RECORDS FOR \u3ci\u3eACERIA ANTHOCOPTES\u3c/i\u3e (ACARI: ERIOPHYIDAE) OCCURRING ON CANADA THISTLE IN COLORADO, NEBRASKA, AND WYOMING, U.S.A.

Canada thistle [Cirsium arvense (L.) Scop.] growing in eastern Colorado, Wyoming and western Nebraska were surveyed for the presence and distribution of Aceria anthocoptes (Nal.). Of the 34 sites surveyed in 2004, mites were abundant at 42%, present in lesser numbers at 52%, and not present at 6% of the sites. In 2005, two new sites were added and ten sites sampled in 2004 were revisited. Of these 12 sites, mites were abundant at 17%, present to a lesser extent at 58%, and not present at 25% of the sites. The results demonstrate that Canada thistle growing in this region commonly harbor A. anthocoptes. How long A. anthocoptes has been present in this region is unknown, however, anecdotal evidence demonstrating a dramatic decline in the population of Canada thistle at one Colorado site from 2000 to 2007 suggests that the mite may have been present since 2002

The operationalized psychodynamic diagnostics system. Clinical relevance, reliability and validity

In this paper, we present a multiaxial system for psychodynamic diagnosis, which has attained wide usage in Germany in the last 10 years. First we will discuss the 4 operationalized psychodynamic diagnostics (OPD) axes: illness experience and treatment assumptions, relationships, mental conflicts, and structure, then clinical applications will be outlined. Focus psychodynamic formulations can be employed both with inpatients and with outpatients. Studies show good reliability in a research context and acceptable reliability for clinical purposes. Validity will be separately summarized as content, criterion, and construct validity. Validity studies indicate good validity for the individual axes. Numerous studies on the OPD indicate areas of possible improvement, for example for clinical purposes the OPD should be more practically formulated

Deforming glassy polystyrene: Influence of pressure, thermal history, and deformation mode on yielding and hardening

The toughness of a polymer glass is determined by the interplay of yielding, strain softening, and strain hardening. Molecular-dynamics simulations of a typical polymer glass, atactic polystyrene, under the influence of active deformation have been carried out to enlighten these processes. It is observed that the dominant interaction for the yield peak is of interchain nature and for the strain hardening of intrachain nature. A connection is made with the microscopic cage-to-cage motion. It is found that the deformation does not lead to complete erasure of the thermal history but that differences persist at large length scales. Also we find that the strain-hardening modulus increases with increasing external pressure. This new observation cannot be explained by current theories such as the one based on the entanglement picture and the inclusion of this effect will lead to an improvement in constitutive modeling

COMPARISONS OF TWO SYMMETRIC DENSITY FUNCTION SOLUTIONS OF APHID POPULATION GROWTH MODELS

Aphids are among the world\u27s most devastating crop pests, and their population trajectories in field crops are characterized by rapid boom and bust, under the influence of bottom up (host plant) and top down (natural enemy) forces. Theoretical development in aphid growth trajectory modeling has recently advanced quite significantly, and the logistic and normal probability density functions have been found to provide analytical solutions to mechanistic models of the aphid population growth dynamics. The logistic or hyperbolic secant squared model captures a growth trajectory shaped by negative feedback of the aphid population on itself, due to the accumulation of adverse effect on its host plant and the coupling with natural enemies (bottom up as well as top down effect), while the normal model can be derived on the basis of a relationship between intrinsic growth rate and the host plant phenology. In this paper, we fit both models to a large number of observed aphid population trajectors and explore model properties. It is shown that, despite the diverging mechanistic underpinnings of the model, the generated growth curves, as fitted to the data, are very similar, as are characteristics, such as the height of the peak, the time of the peak and the accumulated area under the curve. Both models are useful workhorses for capturing aphid growth dynamics, but fitting one or either model cannot be used as evidence for the underpinning mechanisms, as different underpinning mechanisms result in similar population dynamics