Experimental study of the detachment and the reattachment of an airflow along an inclined wall controlled by a surface corona discharge-application to a plane turbulent mixing layer

This paper analyzes experimentally the ability of an electrohydrodynamic actuator to modify the properties of a plane turbulent mixing layer in the wake region of an inclined flat plate (expansion corner). The experiments consists of applying a surface corona discharge established between two electrodes flush mounted on the surface of the test profile. Two cases are investigated. First, one considers the application of the corona to an airflow which is naturally detached at the trailing edge of the test profile and the experiments is repeated with an airflow naturally attached. In this paper, the behavior of the discharge with free air stream up to 35 m/s and measurements by particle image velocimetry for a velocity range from 6 to 16 m/s are presented. The results show that: 1) the discharge regime depends on the free air stream velocity; 2) when the airflow is naturally detached, the corona discharge allows increasing the velocity and the thickness of the mixing layer; 3) when the airflow is naturally attached, it is possible to reduce the velocity and to increase the thickness of the mixing layer; and 4) using a pulse discharge, one observes that the effect of the actuator on the mixing layer is different according to the discharge frequency.     

Stability of electrical properties in polyaniline-polystyrene blends

The thermal stability of free standing polystyrene-polyaniline-DiOHP blend electrical properties is described. Electrical conductivity measurements have been performed at different temperatures for a long degradation time. A good stability with time and temperature is observed. The electrical conductivity variations versus temperature are explained on the assumption of a main contribution of hopping mechanisms between conducting clusters.     

Body composition in children receiving recombinant human growth hormone after renal transplantation

BACKGROUND: Recombinant human growth hormone (rhGH) is an anabolic hormone promoting protein synthesis in various tissues. Therefore, changes in body composition may be expected during rhGH treatment. METHODS: We studied changes in body composition during two years of rhGH treatment in 21 children after at least one year with a functioning renal transplant. The mean +/- SD age was 12.9+/-2.5 years at the start of rhGH therapy. A whole body, dual energy X-ray absorptiometry (DEXA) exam was performed before the initiation of rhGH therapy (T0), and was repeated at one and two year intervals after initiation of the therapy (T1 and T2, respectively). RESULTS: Lean body mass increased by a median of 0.48 SDS during the first year of treatment (P = 0.022), and the median increase during two years of therapy was 0.36 SDS (P = 0.061). On the contrary, the median fat body mass decreased by 2.17 SDS during the T0 to T1 period (P = 0.04) and by 1.99 SDS during the T0 to T2 period (P = 0.055). The index for fat body mass/lean body mass (FBM/LBM) decreased by a median of 5.3% during T0 to T1 (P < 0.001), however, a slower but still significant decrease by a median of 4.2% was noted at T2 (P < 0.05). Bone mass content did not change significantly during rhGH treatment. The medians in caloric and protein intakes were stable during rhGH treatment. CONCLUSION: A significant increase of lean body mass and a decrease of fat body mass was noted during rhGH therapy in children after renal transplantation.     

Dynamic X-ray computed tomography

Dynamic computed tomography (CT) imaging aims at reconstructing image sequences where the dynamic nature of the living human body is of primary interest. The main applications concerned are image-guided interventional procedures, functional studies and cardiac imaging. The introduction of ultra-fast rotating gantries along with multi-row detectors and in near future area detectors allows huge progress toward the imaging of moving organs with low-contrast resolution. This paper gives an overview of the different concepts used in dynamic CT. A new reconstruction algorithm based on a voxel-specific dynamic evolution compensation is also presented. It provides four-dimensional image sequences with accurate spatio-temporal information, where each frame is reconstructed using a long-scan acquisition mode on several half-turns. In the same time, this technique permits to reduce the dose delivered per rotation while keeping the same signal to noise ratio for every frame using an adaptive motion-compensated temporal averaging. Results are illustrated on simulated data.     

A study of the influence of muscovite on the thermal transformations of kaolinite from room temperature up to 1,100 °C

Global thermal transformation of kaolinite–muscovite mixtures containing at most 25 mass % of muscovite was studied up to 1,100 °C. Quantitative and qualitative DTA analysis reveals a great intereaction between the two phylosilicates above 900 °C, which is characterized by an enhancement of spinodal demixion contribution during the structural reorganization of metakaolinite. The corresponding enthalpy variation are respectively −32 ± 1 kJ/mol and −15 ± 1 kJ/mol of kaolinite for pure kaolinite and for the mixture containing 15 mass % of muscovite. This interaction is mainly correlated with the diffusion of potassium ions from muscovite platelets into metakaolinite structure. The resulting consequence is an enhancement of mullite crystallization and grain growth at 1,050 °C (earlier than in the case of pure kaolinite mineral).     

Convergence and convergence rate of the balanced realization truncations for infinite-dimensional discrete-time systems

In this paper, we study approximation via balanced realizations for a large class of infinite-dimensional discrete-time linear systems. We give properties of the truncated system and prove that the approximation is L₂-convergent. In the case of nuclear systems, we prove convergence in nuclear norm and give an estimation of the L_∞-convergence rate.     

Application of multi-domain decomposition method to solve EMCproblem on an aeroplane

The authors describe a multi-domain decomposition method using an FVTD technique for the resolution of an electromagnetic problem on vehicles composed of several volumes. In particular, they evaluate the current on a cable inside the volume of an aeroplane. The results obtained show an important gain in time compared to a complete FVTD method