9,215 research outputs found
Wind trajectory tracing for air pollution studies (AIRPOL)
Wind trajectory computer program, consisting of data handling program and analysis program, traces Los Angeles Basin wind patterns either backward or forward in time. Program may be applicable to other areas
Recent Measurements at JPL of Particle Size of Aluminum Oxide from Small Rocket Motors
Small rocket engine test firings conducted to measure particle size distribution of aluminum oxide exhaust
Impurity transport in temperature gradient driven turbulence
In the present paper the transport of impurities driven by trapped electron
(TE) mode turbulence is studied. Non-linear (NL) gyrokinetic simulations using
the code GENE are compared with results from quasilinear (QL) gyrokinetic
simulations and a computationally efficient fluid model. The main focus is on
model comparisons for electron temperature gra- dient driven turbulence
regarding the sign of the convective impurity velocity (pinch) and the impurity
density gradient R/LnZ (peaking factor) for zero impurity flux. In particular,
the scaling of the impurity peaking factors with impurity charge Z and with
driving temper- ature gradient is investigated and compared with the results
for Ion Temperature Gradient (ITG) driven turbulence. In addition, the impurity
peaking is compared to the main ion peaking obtained by a self-consistent fluid
calculation of the density gradients corresponding to zero particle fluxes.
For the scaling of the peaking factor with impurity charge Z, a weak
dependence is obtained from NL GENE and fluid simulations. The QL GENE results
show a stronger dependence for low Z impurities and overestimates the peaking
factor by up to a factor of two in this region. As in the case of ITG dominated
turbulence, the peaking factors saturate as Z increases, at a level much below
neoclassical predictions. However, the scaling with Z is weak or reversed as
compared to the ITG case.
The scaling of impurity peaking with the background temperature gradients is
found to be weak in the NL GENE and fluid simulations. The QL results are also
here found to significantly overestimate the peaking factor for low Z values.
For the parameters considered, the background density gradient for zero
particle flux is found to be slightly larger than the corresponding impurity
zero flux gradient.Comment: 23 pages, 13 figures. Submitted to AIP: Physics of Plasma
A comparison of two methods of measuring particle size of Al2O3 produced by a small rocket motor
The size of aluminum oxide particles produced by small rocket motors is determined by tank collection and spectrophotometry. The size of the particulate determines loss in thrust due to particle lag, particulate radiant heat transfer, acoustic attenuation and impingement and rocket plume structure and properties
Educational aspirations in inner city schools
The research aimed to assess the nature and level of pupils’ educational aspirations and to elucidate the factors that influence these aspirations. A sample of five inner city comprehensive secondary schools were selected by their Local Authority because of poor pupil attendance, below average examination results and low rates of continuing in full-time education after the age of 16. Schools were all ethnically mixed and co-educational. Over 800 pupils aged 12-14 completed a questionnaire assessing pupils’ experience of home, school and their peers. A sub-sample of 48 pupils selected by teachers to reflect ethnicity and ability levels in individual schools also participated in detailed focus group interviews. There were no significant differences in aspirations by gender or year group, but differences between ethnic groups were marked. Black African, Asian Other and Pakistani groups had significantly higher educational aspirations than the White British group, who had the lowest aspirations. The results suggest the high aspirations of Black African, Asian Other and Pakistani pupils are mediated through strong academic self-concept, positive peer support, a commitment to schooling and high educational aspirations in the home. They also suggest that low educational aspirations may have different mediating influences in different ethnic groups. The low aspirations of White British pupils seem to relate most strongly to poor academic self-concept and low educational aspirations in the home, while for Black Caribbean pupils disaffection, negative peers and low commitment to schooling appear more relevant. Interviews with pupils corroborated the above findings and further illuminated the factors students described as important in their educational aspirations. The results are discussed in relation to theories of aspiration which stress its nature as a cultural capacity
Ancient Bonds, Contemporary Powers: Investigating the Causes of Center/Periphery Conflict in the Russian Federation
What are the real causes of conflict between the federal regions and central authority in the Russian Federation? Why is it that some regions are compelled to act assertively towards Moscow, while others are not? These questions are relevant for any actor concerned with Russian affairs; moreover, they represent a critical debate for those who hope to bring aid to Russia’s struggling regional populations. This research furthers the debate through a test of the two major schools of ethno-federal thought: primordialism and bargaining theory. The study (1) identifies relevant variables, (2) constructs indices to represent each of the theories, and (3) tests those indices for correlation with regional aggression. This research shows that characteristics suggested by both primordialism and bargaining theory exert influence on regional aggression; however, it also finds that bargaining theory more accurately explains the behavior of Russian regions. In the end, this study concludes that ethnic differences, per se, do not lead to center/periphery conflict in the Russian Federation
Pupil mobility, attainment and progress in secondary school
This paper is the second of two articles arising from a study of the association between pupil mobility and attainment in national tests and examinations in an inner London borough. The first article (Strand & Demie, 2006) examined the association of pupil mobility with attainment and progress during primary school. It concluded that pupil mobility had little impact on performance in national tests at age 11, once pupils’ prior attainment at age 7 and other pupil background factors such as age, sex, special educational needs, stage of fluency in English and socio-economic disadvantage were taken into account. The present article reports the results for secondary schools (age 11-16). The results indicate that pupil mobility continues to have a significant negative association with performance in public examinations at age 16, even after including statistical controls for prior attainment at age 11 and other pupil background factors. Possible reasons for the contrasting results across school phases are explored. The implications for policy and further research are discussed
Double precision trajectory program /DPTRAJ 2.2C/
Four part program computes trajectory of space probe moving in solar system and subject to variety of forces
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