Turbulence in a gaseous hydrogen-liquid oxygen rocket combustion chamber

The intensity of turbulence and the Lagrangian correlation coefficient for a LOX-GH2 rocket combustion chamber was determined from experimental measurements of tracer gas diffusion. A combination of Taylor's turbulent diffusion theory and a numerical method for solving the conservation equations of fluid mechanics was used to calculate these quantities. Taylor's theory was extended to consider the inhomogeneity of the turbulence field in the axial direction of the combustion chamber, and an exponential function was used to represent the Lagrangian correlation coefficient. The results indicate that the value of the intensity of turbulence reaches a maximum of 14% at a location about 7" downstream from the injector. The Lagrangian correlation coefficient associated with this value is given by the above exponential expression where alpha = 10,000/sec

Influence of different eCG doses on the rabbit doe ovary response, fertilizing aptitude and embryo development

[EN] The aim of this experiment was to compare the ovary response, the fertilising aptitude and the embryo development of multiparous rabbit does having received during the whole career 0 (control: no injection, group 0), 8 or 25 IU of eCG (groups 8 and 25, respectively) 48 h before each 4 d post partum insemination. After the 11th series of insemination, two groups of 60 does were sacrifi ced 30 h or 14 d after insemination. The percentage of ovulating females does not vary according to the eCG treatment, but the ovulation rate (number of corpora lutea per ovulating does) and the fertilising rate (number of segmented ova/number of corpora lutea x100) increases with eCG dose [10.2, 11.1, 12.3 corpora lutea (P=0.011); 61.6 vs 97.5, 81.2% (P<0.001), for groups 0, 8 and 25 IU respectively]. In a same way, at 14 d of pregnancy, the embryo survival (1-(number of corpora lutea ¿ number of alive embryos/ number of corpora lutea)) increases with the injected amount of eCG (55.1 vs 69.9 and 83.1% for groups 0, 8 and 25, respectively, P=0.023). Moreover, eCG completely removes the fertilising failure independent of ovulation. Compared with the other does, lactating-non-receptive does have a lower fertilisation rate (70.0 vs 90.2%, P=0.008) and a weaker embryo survival (55.3 vs 83.5%, P<0.001). It is concluded that with intensive reproduction rhythm (4 d post partum insemination), an 8 IU of eCG injected 48 h before insemination is enough to enhance the ovulation rate, the embryo survival and the fertilisation rate of multiparous does.Ttheau-Clément, M.; Lebas, F.; Falières, J. (2010). Influence of different eCG doses on the rabbit doe ovary response, fertilizing aptitude and embryo development. World Rabbit Science. 16(2). doi:10.4995/wrs.2008.62916

Maximizing AUV slow speed performance

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1997.Includes bibliographical references (leaves 101-104).by Phillip J. LeBas.M.S

High-contrast 10-fs OPCPA-based Front-End for the Apollon-10PW laser (Orale)

International audienceWe present a high-contrast 10-fs Front-End for Ti:sapphire PW-lasers within the Apollon-10PW project. This injector uses OPCPA pumped at 100 Hz by Yb-based CPA chain. Combination of OPCPA and XPW permits a >10 12 contrast ratio

Effect of different weaning age (21, 28 or 35 days) on production, growth and certain parameters of the digestive tract in rabbits

The effect of different weaning ages, that is, 21 (G21), 28 (G28) or 35 (G35) days, on growth and certain parameters of the digestive tract was examined in rabbits to assess the risk of early weaning attributable to the less-developed digestive system. On days 35 and 42, G35 rabbits had 10% to 14% and 10% higher BW, respectively ( P,0.05), than those weaned at days 21 and 28. In the 4th week of life, early weaned animals had 75% higher feed intake than G28 and G35 rabbits ( P,0.05). The relative weight of the liver increased by 62% between 21 and 28 days of age, and thereafter it decreased by 76% between 35 and 42 days of age ( P,0.05), with G21 rabbits having 29% higher weight compared with G35 animals on day 35 ( P,0.05). The relative weight of the whole gastrointestinal (GI) tract increased by 49% and 22% after weaning in G21 and G28 rabbits, respectively ( P,0.05). On day 28, the relative weight of the GI tract was 19% higher in G21 than in G28 rabbits, whereas on day 35 G21 and G28 animals had a 12% heavier GI tract compared with G35 rabbits ( P,0.05). Age influenced the ratio of stomach, small intestine and caecum within the GI tract; however, no effect of different weaning age was demonstrated. The pH value of the stomach and caecum decreased from 5.7 to 1.6 and from 7.1 to 6.3, respectively, whereas that of the small intestine increased from 6.8 to 8.4 ( P,0.05); the differences between groups were not statistically significant. Strictly anaerobic culturable bacteria were present in the caecum in high amounts (108), already at 14 days of age; no significant difference attributable to weaning age was demonstrable. The concentration of total volatile fatty acids (tVFA) was higher in G21 than in G28 and G35 throughout the experimental period ( P,0.05). The proportion of acetic and butyric acid within tVFA increased, whereas that of propionic acid decreased, resulting in a C3 : C4 ratio decreasing with age. Early weaning (G21) resulted in higher butyric acid and lower propionic acid proportions on day 28 ( P,0.05). No interaction between age and treatment was found, except in relative weight of the GI tract and caecal content. In conclusion, early weaning did not cause considerable changes in the digestive physiological parameters measured, but it resulted in 10% lower growth in rabbits