13 research outputs found
Rarefied flow past a flat plate at incidence
Results of a numerical study using the direct simulation Monte Carlo (DSMC) method are presented for the transitional flow about a flat plate at 40 deg incidence. The plate has zero thickness and a length of 1.0 m. The flow conditions simulated are those experienced by the Shuttle Orbiter during reentry at 7.5 km/s. The range of freestream conditions are such that the freestream Knudsen number values are between 0.02 and 8.4, i.e., conditions that encompass most of the transitional flow regime. The DSMC simulations show that transitional effects are evident when compared with free molecule results for all cases considered. The calculated results demonstrate clearly the necessity of having a means of identifying the effects of transitional flow when making aerodynamic flight measurements as are currently being made with the Space Shuttle Orbiter vehicles. Previous flight data analyses have relied exclusively on adjustments in the gas-surface interaction models without accounting for the transitional effect which can be comparable in magnitude. The present calculations show that the transitional effect at 175 km would increase the Space Shuttle Orbiter lift-drag ratio by 90 percent over the free molecule value
DSMC simulations of Mach 20 nitrogen flows about a 70 degree blunted cone and its wake
Numerical results obtained with the direct simulation Monte Carlo (DSMC) method are presented for Mach 20 nitrogen flow about a 70-deg blunted cone. The flow conditions simulated are those that can be obtained in existing low-density hypersonic wind tunnels. Three sets of flow conditions are simulated with freestream Knudsen numbers ranging from 0.03 to 0.001. The focus is to characterize the wake flow under rarefied conditions. This is accomplished by calculating the influence of rarefaction on wake structure along with the impact that an afterbody has on flow features. This data report presents extensive information concerning flowfield features and surface quantities
Effects of Chemistry on Blunt-Body Wake Structure
Results of a numerical study are presented for hypersonic low-density flow about a 70-deg blunt cone using direct simulation Monte Carlo (DSMC) and Navier-Stokes calculations. Particular emphasis is given to the effects of chemistry on the near-wake structure and on the surface quantities and the comparison of the DSMC results with the Navier-Stokes calculations. The flow conditions simulated are those experienced by a space vehicle at an altitude of 85 km and a velocity of 7 km/s during Earth entry. A steady vortex forms in the near wake for these freestream conditions for both chemically reactive and nonreactive air gas models. The size (axial length) of the vortex for the reactive air calculations is 25% larger than that of the nonreactive air calculations. The forebody surface quantities are less sensitive to the chemistry than the base surface quantities. The presence of the afterbody has no effect on the forebody flow structure or the surface quantities. The comparisons of DSMC and Navier-Stokes calculations show good agreement for the wake structure and the forebody surface quantities
Adult onset pityriasis rubra pilaris
Pityriasis rubra pilaris (PRP) has always been an intriguing topic ever
since its inception. It is a group of chronic disorders characterized
by reddish orange plaques with pityriasiform scaling showing follicular
keratoses, palmoplantar keratoderma, and sometimes, erythroderma. It
occurs all over the world but with racial variations. Its incidence
might vary and the age at onset, behavior, clinical appearance, and
prognosis are considered to be very important for its classification.
It may manifest either as Type I classical adult onset PRP, Type II
atypical adult (onset) PRP, or Type VI PRP (HIV-associated PRP
pityriasis rubra pilaris) in contrast to classical juvenile (Type III)
and circumscribed juvenile (Type IV) encountered among children. Its
diagnosis is largely clinical with microscopic pathology being a useful
supplement, but it continues to be a therapeutic dilemma. We review the
epidemiology of adult onset PRP here and take stock of the prevalent
treatment options
Psoriasiform dermatoses
Psoriasiform reaction pattern is a commonly encountered denominator in
a wide variety of unrelated disorders. It may be a reaction to either
the internal or the external environmental, allergic, infective,
parasitic, bacterial, fungal, viral and/or malignant stimuli. The
degree of evolution of such a pattern and its significance vary
according to the dermatosis. The age of the skin lesions may also
influence the histopathological presentation and its
clinico-histopathological disparity can often bewilder an expert.
However, such a situation warrants more astute and sustained
observations to unveil the exact underlying condition(s). Thus,
psoriasiform dermatoses should only be an initial caption until an
exact dermatological disorder is defined. There has been greater number
of instances of psoriasiform drug eruptions where a confirmation of the
diagnosis can be achieved after their remission by doing a provocation
test. Similarly, such instances have also been on the rise in
HIV/AIDS-affected individuals all over the world. Besides mycosis
fungoides and Hodgkin′s disease, several unrelated malignancies
have been preceded or accompanied by psoriasiform skin eruptions
Not Available
Not AvailableBioinoculants serve as a promising, eco-friendly alternative to conventional chemical fertilizers and
pesticides. While their direct positive effect on plant growth is well known, non-target effects of these
agricultural amendments have so far not been extensively studied. The present study is an attempt to
assess (a) the survival of Bacillus megaterium, Pseudomonas fluorescens and Azotobacter chroococcum in the
rhizosphere of Cajanus cajan (pigeon pea), (b) the target effects of unconventional combinations of these
bioinoculants on the crop, and (c) the non-target effects (on the resident soil microflora) of the bacterial
supplements, when applied individually and in combination. Rifampicin-resistant strains were
employed to follow the persistence of the bioinoculants in the rhizosphere. They could be detected
until approximately two months after sowing. The effect of the bioinoculants in the
field was assessed on
various plant growth parameters. Triple inoculation competed well with chemical fertilizer with respect
to plant growth parameters. Grain yield (kg ha 1) was 1.5- and 1.7-fold higher with mixed consortium
and chemical fertilizer, respectively, than that of the untreated control. A cultivation-dependent
approach was employed to assess important microbial groups in the plant rhizosphere. In a comparison
of the treatments with bulk soil, a clear effect on the rhizosphere was apparent. Apart from the
inoculation effect, pronounced changes in the microbial diversity were observed during plant
development. At the vegetative stage, the mixed consortium showed increases of 1.08-, 1.22- and
4.2-fold in the abundance of nitrogen
fixers, Pseudomonas and Actinomycetes, respectively, as compared
to the untreated control. Additionally, the bioinoculants were found to be compatible with other groups
of plant growth promoting rhizobacteria.Not Availabl