Combustion instability prediction using a nonlinear bipropellant vaporization model

Combustion instability prediction using nonlinear bipropellant vaporization mode

The measurements of vehicle glow on the Space Shuttle

From the combined data set of glow observations on STS-3, STS-4 and STS-5 some of the properties of the shuttle glow were observed. Comparison of the STS-3 (240 km) and STS-5 (305 km) photographs show that the intensity of the glow is about a factor of 3.5 brighter on the low altitude (STS-3) flight. The orbiter was purposely rotated about the x axis in an experiment on STS-5 to observe the dependence of the intensity on the angle of incidence between the spacecraft surface normal and the velocity vector. For a relatively large angle between the velocity vector and the surface normal there is an appreciable glow, provided the surface is not shadowed by some other spacecraft structure. As the angle becomes less the glow intensifies. The grating experiments (STS-4 photography only, STS-5 image intensifier photography) provided a preliminary low resolution spectra of the spacecraft glow. Accurate wavelength calibrations of the STS-5 instrument permitted measuring of the spectrum and intensity of the Earth's airglow

Electrical properties of breast cancer cells from impedance measurement of cell suspensions

Impedance spectroscopy of biological cells has been used to monitor cell status, e.g. cell proliferation, viability, etc. It is also a fundamental method for the study of the electrical properties of cells which has been utilised for cell identification in investigations of cell behaviour in the presence of an applied electric field, e.g. electroporation. There are two standard methods for impedance measurement on cells. The use of microelectrodes for single cell impedance measurement is one method to realise the measurement, but the variations between individual cells introduce significant measurement errors. Another method to measure electrical properties is by the measurement of cell suspensions, i.e. a group of cells within a culture medium or buffer. This paper presents an investigation of the impedance of normal and cancerous breast cells in suspension using the Maxwell-Wagner mixture theory to analyse the results and extract the electrical parameters of a single cell. The results show that normal and different stages of cancer breast cells can be distinguished by the conductivity presented by each cell. © 2010 IOP Publishing Ltd

Momentum Transfer Between Polydisperse Particles in Dense Granular Flow

We perform molecular dynamics (MD) simulations (based on the soft-sphere model) of a model dry granular system consisting of two types of spherical particles differing in size and/or density to characterize particle-particle momentum transfer (solid drag). The velocity difference between two types of particles is specified in the initial conditions, and the evolution of relative mean velocity and the velocity fluctuations in terms of granular temperature are quantified. The dependence of the momentum transfer is studied as a function of volume fraction, size and density ratio of the two types of particles, inelasticity, and friction coefficient. An existing continuum model of particle-particle momentum transfer is compared to the MD simulations. A modified continuum solid drag model is suggested for a limited range of parameters

Amphibians and Reptiles Captured in Drift Fences in Northwest Wisconsin Pine Barrens

Drift fence surveys were initiated by the Wisconsin Department of Natural Resources (WDNR) in the Crex Meadows Wildlife Area (CMWA) in 1993. Systematic drift fence trapping of amphibians and reptiles in the northwest pine barrens was conducted in a 1996- 97 cooperative effort by the WDNR, the U.S. Forest Service (USFS), and the Great Lakes Indian Fish and Wildlife Commission (GLIFWC). Drift fences were operated in four managed barrens properties, the CMWA, Namekagon Barrens Wildlife Area (NBWA), the Douglas County Wildlife Area (DCWA), and the Moquah Barrens Wildlife Area (MBWA). Eighteen amphibian and reptile species (four salamanders, eight anurans, one turtle, one lizard, four snakes) were captured in ten drift fences in the Northwest Wisconsin Pine Barrens. Fourteen species were captured in the CMWA. The most common species were chorus frogs (Pseudacris triseriata ssp.), wood frogs (Rana sylvatica), and northern spring peepers (P. c. crucifer). The relative abundance of the amphibians and reptiles captured, expressed as mean 1996-97 catch per effort, did not differ between the four managed properties, but species composition did. Only three species were common to all four properties, the blue-spotted salamander (Ambystoma laterale), the eastern American toad (Bufo a. americanus), and the spring peeper. The most likely reason that species composition differs is that the Northwest Wisconsin Pine Barrens is an ecotone for amphibian and reptile species of the western prairies (e.g. tiger salamanders, Ambystoma t. tigrinum) and species of the eastern forests (e.g. spotted salamanders, A. maculatum). All but three tiger salamanders were captured in the southwesternmost property (CMWA) whereas the spotted salamander was captured only in the northeastern-most property (MBWA). Annual variation in CMWA catch/effort rates occurred in total amphibians and reptiles and individual species captured. Total April-May precipitation did not appear to support the catch/effort variation from year to year. However, when broken down into five-day periods, increased catch/effort rates were significantly correlated to precipitation increases, but not to changes in temperature. Timing and amount of precipitation within the breeding season may have impacted herptile movements in the CMWA

Proper Grazing = More Profit.

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Do You Know Your Range Grasses?

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Blueshifted galaxies in the Virgo Cluster

We examine a sample of 65 galaxies in the Virgo cluster with negative radial velocities relative to the Local Group. Some features of this sample are pointed out. All of these objects are positioned compactly within a virial zone of radius 6{\deg} in the cluster, but their centroid is displaced relative to the dynamic center of the cluster, M87, by 1.1{\deg} to the northwest. The dwarf galaxies in this sample are clumped on a scale of ~10' (50 kpc). The observed asymmetry in the distribution of the blueshifted galaxies may be caused by infall of a group of galaxies around M86 onto the main body of the cluster. We offer another attempt to explain this phenomenon, assuming a mutual tangential velocity of ~300 km/s between the Local Group and the Virgo cluster owing to their being repelled from the local cosmological void.Comment: 10 pages, 4 figures, 1 table. Published in Astrophysics, Vol. 53, No. 1, pp. 32-41, 201