4, in both internal (channel) and external (airfoil) flows. A review of the boundary-layer parameters characterizing the pressure gradient effects is provided, and the more relevant ones are introduced as new variables in the model. The method is then compared to the zero pressure gradient model it is derived from. The influence of the pressure gradient on the wall-pressure spectrum is discussed.Finally,themethodisappliedtoprovideinputdataofaradiatedtrailing-edge noisemodelbymeansofan aeroacoustic analogy, namely Amiet’s theory of turbulent boundary layer past a trailing edge. The results are compared to experimental data obtained in an open-jet anechoic wind tunnel.

Direct measurements of the wavenumber-frequency spectrum of wall pressure fluctuations beneath a turbulent plane channel flow have been performed in an anechoic wind tunnel. A rotative array has been designed that allows the measurement of a complete map, 63×63 measuring points, of cross-power spectral densities over a large area. An original post-processing has been developed to separate the acoustic and the aerodynamic exciting loadings by transforming space-frequency data into wavenumber-frequency spectra. The acoustic part has also been estimated from a simple Corcos-like model including the contribution of a diffuse sound field. The measured acoustic contribution to the surface pressure fluctuations is 5% of the measured aerodynamic surface pressure fluctuations for a velocity and boundary layer thickness relevant for automotive interior noise applications. This shows that for aerodynamically induced car interior noise, both contributions to the surface pressure fluctuations on car windows have to be taken into account.

OBJECT:The authors analyzed the long-term results and radiological aspects of sphenoorbital meningioma (with emphasis on exophthalmos) in a series of 30 patients who underwent resection.METHODS:Data obtained in all 30 patients who underwent surgery for typical sphenoorbital meningioma at the authors' institution between June 1994 and September 2005 were analyzed retrospectively. The exophthalmos index (EI) was measured on preoperative MR images and/or CT scans and compared between the early and last follow-up examinations. All patients were women 35-74 years of age (median 51 years). Exophthalmos was the presenting symptom in 28 patients (93%), and was observed on preoperative MR images in all patients. The median duration of symptoms before surgery was 10 months (2-120 months).RESULTS:Total resection (Simpson Grade I) was not achieved in these patients because of the impossibility of resecting the dura mater in the superior orbital fissure without causing significant complications. Subtotal resection (Simpson Grade II) was obtained in 90% of patients, and in 3 patients (10%) a portion of the tumor was deliberately left in place because of extensive macroscopic infiltration of the cavernous sinus and/or extraocular muscles (Simpson Grade III). No patient died. Radiological evaluation at a median follow-up of 61 months (range 17-136 months) showed no contrast enhancement in 14 patients (47%), residual contrast enhancement without evolution in 13 (43%), and recurrence (new contrast enhancement) in 3 (10%). The EI was improved at the first radiological follow-up (median 12 months) in 27 patients (90%), and at the last radiological follow-up (median 61 months) in 28 patients (93%). In the interval between the first and final imaging follow-up, the EI improved in only 8 patients (20%), worsened in 15 patients (50%), and showed no variation in 7 patients (30%).CONCLUSIONS:Sphenoorbital meningiomas are insidious tumors with slow progression. Even when exophthalmos is not clinically evident, it is always present on preoperative MR imaging. Total resection is not possible due to superior orbital fissure invasion, but subtotal resection (Simpson Grade II) can assure long-term stability due to the nonevolutive nature of most residual tumors. Exophthalmos improves at early radiological follow-up, but may worsen again as time passes.

The prediction of the vibratory response of structures excited by turbulent flows implies a good knowledge of both aerodynamic and acoustic components of the wall pressure fluctuations. In the present work, experiments were aimed at measuring wall pressure fluctuations under turbulent flows, in order to separate the two exciting loadings. The experiments were conducted in the anechoic wind tunnel of Ecole Centrale de Lyon (France). Two configurations were more precisely studied : a turbulent boundary layer and a cylindrical bar in crossflow. A rotative array has been designed that allows the measurement of a complete map of cross-power spectral densities over a large area. A post-processing has been developed to transform the space-frequency data into wavenumber-frequency spectra. Results for the boundary layer are consistent with the Corcos model. Analysis of the spectra shows the presence of an acoustic pressure field, which magnitude is about 5% of the aerodynamic pressure field. Concerning the bar, the whistling frequencies do appear on wavenumber spectra, but not the broadband acoustic field previously observed for the boundary layer. Besides, the strong flow inhomogeneity makes quality of wavenumber spectra worse.

Solid Oxide Fuel Cell (SOFC) application development is very well represented in Switzerland by two companies. Sulzer Hexis AG is one of the world leaders in the commercialization of SOFC systems for single family houses. A smaller company, HTceramix, is active in novel processing routes for cells and in innovative stack designs. This article first presents the benefits of implementing SOFC in selected applications and markets. Then the current state-of-the-art in stacking is described for both Swiss stack designs, looking at power density, and electrical efficiency. It is remarkable that both stacks currently exhibit a unique characteristic in SOFC design: the absence of side sealing, which permits to significantly simplify the stack assembly and thus improve its reliability. Finally, the two generations of SOFC systems produced by Sulzer Hexis are presented. The HXS 1000 Premiere preseries system is evaluated on the basis of the extended demonstration program currently underway where 110 systems are in operation in single family houses and public buildings. The near-series system is then introduced with respect to the identified needs in reduction of investment and operating costs as well as size and weight.

Transparent single crystals of Pb(Zn-1/3, Nb-2/3)O-3-PbTiO3 (PZN-PT) perovskite have been grown by the slow cooling method in a temperature gradient furnace. The optimization of growth techniques to crystallize PZN-PT with a cubic habitus is described in details. The growth temperature range and cooling rates was carried out in different lead fluxes, Crystal recovery from the residual flux was obtained by different techniques based on liquid flux elimination at the end of the growth process. The best transparent single crystals of PZN-PT, obtained by a cooling at 0.8 degrees C/h from 1150 degrees C to 930 degrees C, had a cubic habitus and a size of approx.: 4 x 4 x 2.5 mm(3). The chemical composition and the homogeneity of the crystals were tested by electron probe micro-analysis. Crystals characterization was performed using polarized light microscopy and dielectric and piezoelectric measurements. Phase transitions were determined by differential scanning calorimetry, optical and dielectric measurements.

Transparent single crystals of Pb(Zn1/3, Nb2/3)O3–PbTiO3 (PZN–PT) perovskite have been grown by the slow cooling method in a temperature gradient furnace. The optimization of growth techniques to crystallize PZN–PT with a cubic habitus is described in details. The growth temperature range and cooling rates was carried out in different lead fluxes. Crystal recovery from the residual flux was obtained by different techniques based on liquid flux elimination at the end of the growth process. The best transparent single crystals of PZN–PT, obtained by a cooling at 0.8°C/h from 1150°C to 930°C, had a cubic habitus and a size of approx.: 4×4×2.5 mm3. The chemical composition and the homogeneity of the crystals were tested by electron probe micro-analysis. Crystals characterization was performed using polarized light microscopy and dielectric and piezoelectric measurements. Phase transitions were determined by differential scanning calorimetry, optical and dielectric measurements.

Optimal feedback control was designed and successfully implemented to reduce the vibrations of a steel plate excited by a turbulent boundary layer. One side of the plate was equipped with piezoelectric sensors and actuators. The other side was imbedded in the wall of the CNRS-LMFA anechoic wind tunnel. Measurements of the wall pressure at flow speed ranging from 70 to 130 m/s showed that the plate was excited by a standard boundary layer; the parameters of a Corcos model for the wall pressure were identified from flow data. For control a state-space model for the plate was first identified from the actuator-to-sensor transfer functions; nine plate modes in the 0–1000-Hz range were taken into account. Covariance matrices for the boundary layer excitation were also identified from vibration data. An optimal linear quadratic Gaussian (LQG) controller was then designed from the plate and noise model. The LQG algorithm was implemented on the CNRS-LMA multichannel control system and tested at three flow velocities. A 10-dB reduction of the vibration level was achieved for the three modes mostly excited by the boundary layer.

We report a case of primary orbital varix treated by embolization with coils after surgical exposure and puncture of the venous ectasia. This method of treatment has the advantage of limiting traumatic dissection and avoiding difficult venous catheterization.

Giant middle cerebral artery (MCA) trifurcation aneurysms that cannot be excluded directly can be treated by flow inversion achieved by creation of an extracranial-intracranial bypass distal to the aneurysm, followed by occlusion of the parent vessel proximal to the aneurysm. As opposed to surgical occlusion, endovascular occlusion avoids dissection of the aneurysm area, and the site of occlusion can be chosen according to the flow distribution demonstrated on angiography performed during test occlusions. Two patients with giant aneurysms of the MCA trifurcation benefited from flow inversion treatment. Forty-eight hours after an MCA-superficial temporal artery bypass had been created, the M1 segment was occluded by inserting a coil in the first patient and the internal carotid artery was occluded with balloons in the second patient (there was no communicating artery in the latter case). Both occlusions were performed immediately after a clinical test of occlusion tolerance. The patients were clinically intact during the postoperative course. Follow-up angiography performed 11 and 4 months, respectively, after vessel occlusion showed that the aneurysm occlusion was stable.

A phase diagram based on dielectric‐permittivity‐versus‐temperature measurements and high‐temperature X‐ray diffractometry was proposed for 0.4Pb(Ni1/3,Nb1/3)O3‐xPbZrO3‐(0.6‐x)PbTiO3(0.2 lessthan equal toxlessthan equal to 0.32) relaxor‐ferroelectric solid solution, and a morphotropic phase boundary that sharply bends toward zirconium‐rich compositions was found. A spontaneous normal‐to‐relaxor ferroelectric transition was also observed when heating was performed for all the compositions tested near the morphotropic phase boundary. Additional considerations about previously published phase diagrams for Pb(Zn1/3,Nb2/3)O3‐PbTiO3and Pb(Mg1/3,Nb1/3)O3‐PbTiO3might lead to an extension of the presented diagram to these compositions.

Wall-pressure fluctuations can be represented by a spectrum level that is a function of flow-direction wavenumber and frequnecy, Φ (k1, ω). In the theory developed herein the frequency is replaced by a phase speed; ω = ck1. At low wavenumbers the spectrum is a universal function if nondimensionalized by the friction velocity u* and the boundary layer thickness δ, while at high wavenumbers another universal function holds if nondimensionalized by u* and viscosity ν. The theory predicts that at moderate wavenumbers the spectrum must be of the form Φ+ (k+1, ω+ = c+ k+1) = k+1 − 2 P+ (Δc+) where P+ (Δc+) is a universal function. Here Δc+ is the difference between the phase speed and the speed for which the maximum of Φ+ occurs. Similar laws exist in outer variables. New measurements of the wall-pressure are given for a large Reynolds number range; 45,000 < Re = Uoδ/ν < 113,000. The scaling laws described above were tested with the experimental results and found to be valid. An experimentally determined curve for P+ (Δc+) is given.

Une plaque rectangulaire est utilisée comme filtre spatial et temporel pour mesurer le niveau de la densité interspectrale du champ pariétal de pression sous une couche limite turbulente établie dans l'espace (k, f).Les niveaux obtenus sont confrontés avec les mesures de Martini et comparées aux modèles de Corcos et de Ffowcs Williams.

For many years, SNCF has been concerned with the improvement of the passenger's acoustic comfort. A research program has been defined to study the acoustic phenomena responsible of noise into the high-speed train coaches. A pure tone in the sound spectrum into the coaches evolves with the sleeper spacing and the train speed. This parametric excitation has been already studied as a mechanical phenomenon but the "Couette" flow between the train and the track may generate noise too. The paper presents the test bed set up in the laboratory to reproduce the flow between the coach and the track. The flow characteristics are measured. In some conditions, a pure tone appears in the wall pressure spectrum.