Prediction of forces and moments for hypersonic flight vehicle control effectors

This research project includes three distinct phases. For completeness, all three phases of the work are briefly described in this report. The goal was to develop methods of predicting flight control forces and moments for hypersonic vehicles which could be used in a preliminary design environment. The first phase included a preliminary assessment of subsonic/supersonic panel methods and hypersonic local flow inclination methods for such predictions. While these findings clearly indicated the usefulness of such methods for conceptual design activities, deficiencies exist in some areas. Thus, a second phase of research was conducted in which a better understanding was sought for the reasons behind the successes and failures of the methods considered, particularly for the cases at hypersonic Mach numbers. This second phase involved using computational fluid dynamics methods to examine the flow fields in detail. Through these detailed predictions, the deficiencies in the simple surface inclination methods were determined. In the third phase of this work, an improvement to the surface inclination methods was developed. This used a novel method for including viscous effects by modifying the geometry to include the viscous/shock layer

Doppler imaging of the young late-type star LO Pegasi (BD +22 4409) in September 2003

A Doppler image of the ZAMS late-type rapidly rotating star LO Pegasi, based on spectra acquired between 12 and 15 September 2003, is presented. The Least Square Deconvolution technique is applied to enhance the signal-to-noise ratio of the mean rotational broadened line profiles extracted from the observed spectra. In the present application, a unbroadened spectrum is used as a reference, instead of a simple line list, to improve the deconvolution technique applied to extract the mean profiles. The reconstructed image is similar to those previously obtained from observations taken in 1993 and 1998, and shows that LO Peg photospheric activity is dominated by high-latitude spots with a non-uniform polar cap. The latter seems to be a persistent feature as it has been observed since 1993 with little modifications. Small spots, observed between ~ 10 and ~ 60 degrees of latitude, appears to be different with respect to those present in the 1993 and 1998 maps.Comment: 21 pages, 10 figures, accepted by Monthly Notices of the Royal Astronomical Societ

Constraining Fundamental Physics with Future CMB Experiments

The Planck experiment will soon provide a very accurate measurement of Cosmic Microwave Background anisotropies. This will let cosmologists determine most of the cosmological parameters with unprecedented accuracy. Future experiments will improve and complement the Planck data with better angular resolution and better polarization sensitivity. This unexplored region of the CMB power spectrum contains information on many parameters of interest, including neutrino mass, the number of relativistic particles at recombination, the primordial Helium abundance and the injection of additional ionizing photons by dark matter self-annihilation. We review the imprint of each parameter on the CMB and forecast the constraints achievable by future experiments by performing a Monte Carlo analysis on synthetic realizations of simulated data. We find that next generation satellite missions such as CMBPol could provide valuable constraints with a precision close to that expected in current and near future laboratory experiments. Finally, we discuss the implications of this intersection between cosmology and fundamental physics.Comment: 11 pages, 14 figure

Weekend hospitalization and additional risk of death: An analysis of inpatient data

Objective To assess whether weekend admissions to hospital and/or already being an inpatient on weekend days were associated with any additional mortality risk.Design Retrospective observational survivorship study. We analysed all admissions to the English National Health Service (NHS) during the financial year 2009/10, following up all patients for 30 days after admission and accounting for risk of death associated with diagnosis, co-morbidities, admission history, age, sex, ethnicity, deprivation, seasonality, day of admission and hospital trust, including day of death as a time dependent covariate. The principal analysis was based on time to in-hospital death.Participants National Health Service Hospitals in England.Main Outcome Measures 30 day mortality (in or out of hospital).Results There were 14,217,640 admissions included in the principal analysis, with 187,337 in-hospital deaths reported within 30 days of admission. Admission on weekend days was associated with a considerable increase in risk of subsequent death compared with admission on weekdays, hazard ratio for Sunday versus Wednesday 1.16 (95% CI 1.14 to 1.18; P < .0001), and for Saturday versus Wednesday 1.11 (95% CI 1.09 to 1.13; P < .0001). Hospital stays on weekend days were associated with a lower risk of death than midweek days, hazard ratio for being in hospital on Sunday versus Wednesday 0.92 (95% CI 0.91 to 0.94; P < .0001), and for Saturday versus Wednesday 0.95 (95% CI 0.93 to 0.96; P < .0001). Similar findings were observed on a smaller US data set.Conclusions Admission at the weekend is associated with increased risk of subsequent death within 30 days of admission. The likelihood of death actually occurring is less on a weekend day than on a mid-week day

Queue normalization methods in systems GI/GI/1/m with infinite variance of service time

Queuing systems with an infinite variance of service time are considered. The average waiting time in such systems is equal to infinity at a stationary regime. We analyze the efficiency of introducing of absolute priorities with infinite number of priority classes determined by the special axis marking on intervals for possible values of service time. It is stated that queues in systems become normalized, i.e. the average queue length become finite, when using regular marking. Furthermore, request loss probabilities radically decrease when buffer size is finite. More efficient marking - exponential marking - is proposed for practical purposes in networks with fractal traffic. The optimization problems of regular and exponential markings are solved

Spatiotemporal variations in the abundance, biomass, fecundity, and production of Oithona brevicornis (Copepoda : Cyclopoida) in a West African tropical coastal lagoon (Grand-Lahou, Cote d'Ivoire)

Raphael N'doua Etile, Maryse N'guessan Aka, Aka Marcel Kouassi, Marc Pagano, and Valentin N'douba (2012) Spatiotemporal variations in the abundance, biomass, fecundity, and production of Oithona brevicornis (Copepoda: Cyclopoida) in a West African tropical coastal lagoon (Grand-Lahou, Cote d'Ivoire). Zoological Studies 51(5): 627-643. Oithona brevicornis is a very important zooplankton species in coastal and estuarine aquatic ecosystems of West Africa and was recorded in very high abundances in coastal lagoons of Cote d'Ivoire. To better understand the functional role of this key species, spatio-seasonal variations in O. brevicornis abundance, biomass, fecundity, and production were investigated at 21 stations in Grand-Lahou Lagoon during an annual cycle from Jan. to Dec. 2004. The abundance and biomass showed more or less important spatiotemporal variations. Two peaks were recorded for the mean spatial values in Feb.-Mar. and Sept. During the long (LDS) and short dry seasons (SDS), all developmental stages showed their weakest density and biomass in the channel zone and near the mouth of the Boubo River. During the long (LRS) and short rainy seasons (SRS), O. brevicornis almost disappeared or showed very low abundances (< 1 individual/L) in the northern part and near the channel. Spatiotemporal variations in O. brevicornis fecundity and production showed no particular pattern during the dry seasons (LDS and SDS), while during the rainy seasons (LRS and SRS), very low fecundity and production values were recorded at stations influenced by river inputs. Correlation analyses showed that temperature and salinity were the main variables explaining these spatio-seasonal variations. http://zoolstud.sinica.edu.tw/Journals/51.5/627.pd