Test and evaluation of a solar powered gas turbine system

This paper describes the test and the results of a first prototype solar powered gas turbine system, installed during 2002 in the CESA-1 tower facility at Plataforma Solar de Almería (PSA) in Spain. The main goals of the project were to develop a solar receiver cluster able to provide pressurized air of 1000 °C and solve the problems arising from the coupling of the receivers with a conventional gas turbine to demonstrate the operability of the system. The test set-up consists of the heliostat field of the CESA-1 facility providing the concentrated solar power, a pressurized solar receiver cluster of three modules of 400 kWth each which convert the solar power into heat, and a modified helicopter engine (OST3) with a generator coupled to the grid. The first test phase at PSA started in December 2002 with the goal to reach a temperature level of 800 °C at the combustor air inlet by the integration of solar energy. This objective was achieved by the end of this test phase in March 2003, and the system could be operated at 230 kWe power to grid without major problems. In the second test phase from June 2003 to August 2003 the temperature level was increased to almost 1000 °C. The paper describes the system configuration, the component efficiencies and the operation experiences of the first 100 h of solar operation of this very successful first test of a solar operated Brayton gas turbine system.     

Evidence for non-synchronous rotation of Europa. Galileo Imaging Team

Non-synchronous rotation of Europa was predicted on theoretical grounds, by considering the orbitally averaged torque exerted by Jupiter on the satellite's tidal bulges. If Europa's orbit were circular, or the satellite were comprised of a frictionless fluid without tidal dissipation, this torque would average to zero. However, Europa has a small forced eccentricity e approximately 0.01 , generated by its dynamical interaction with Io and Ganymede, which should cause the equilibrium spin rate of the satellite to be slightly faster than synchronous. Recent gravity data suggest that there may be a permanent asymmetry in Europa's interior mass distribution which is large enough to offset the tidal torque; hence, if non-synchronous rotation is observed, the surface is probably decoupled from the interior by a subsurface layer of liquid or ductile ice. Non-synchronous rotation was invoked to explain Europa's global system of lineaments and an equatorial region of rifting seen in Voyager images. Here we report an analysis of the orientation and distribution of these surface features, based on initial observations made by the Galileo spacecraft. We find evidence that Europa spins faster than the synchronous rate (or did so in the past), consistent with the possibility of a global subsurface ocean.     

Atelectases as part of the convex-sided lungs in thoracic scoliosis (author's transl)

In 4 patients with juvenile idiopathic thoracic scoliosis an atelectasis as part of the convex-sided lungs was found. In all cases there was a small sagittal diameter of the chest; the atelectases were situated in the right lower and middle lobe and caused by the close topographical relation of large bronchi and scoliotic spine (sometimes compression of the bronchus) demonstrable by tomography, bronchoscopy and bronchography. The therapeutic approach of these atelectases is discussed. Thoracic casting either for conservative correction and treatment of scoliosis or as postoperative immobilisation after fusion was done. In all cases, it may influence the occurrence of an atelectasis.     

Properties of coherence-gated wavefront sensing

Coherence-gated wavefront sensing (CGWS) allows the determination of wavefront aberrations in strongly scattering tissue and their correction by adaptive optics. This allows, e.g., the restoration of the diffraction limit in light microscopy. Here, we develop a model, based on ray tracing of ballistic light scattered from a set of discrete scatterers, to characterize CGWS performance as it depends on coherence length, scatterer density, coherence-gate position, and polarization. The model is evaluated by using Monte Carlo simulation and verified against experimental measurements. We show, in particular, that all aberrations needed for adaptive wavefront restoration are correctly sensed if circularly polarized light is used.     

Comparison of 41Ca analysis on 0.5 MV and 5 MV-AMS systems

A comparative study was made between the compact AMS system at the PSI/ETH Laboratory of Ion Beam Physics in Zurich with 0.5 MV terminal voltage and the 5 MV-AMS system at the Scottish Universities Environmental Research Centre (SUERC), Glasgow. Overall 34 urinary samples with ⁴¹Ca/⁴⁰Ca ratios in the range from 4 × 10^?11 to 3 × 10^?10 were processed to CaF₂ and aliquots of the same material were measured on both instruments.Measurements on the compact AMS system were performed in charge state 3+ achieving a transmission of 4% at 1.7 MeV beam energy. Under these conditions a suppression of the interference ⁴¹K is virtually impossible. However, samples with an excess of potassium can be identified by a shift of the ⁴¹Ca/⁴¹K peak in the ΔE ? E histogram of the gas ionization detector employed and a criterion for data rejection can be defined. An overall precision of ～4% and a ⁴¹Ca/⁴⁰Ca background level of 5 × 10^?12 have been reached.For studies with higher demands on the detection limit AMS systems like the one at SUERC are attractive: in charge state 5+ and using a gas stripper beam energy of 27 MeV, a transmission of 5%, a ⁴¹K suppression factor of ～500 and a ⁴¹Ca/⁴⁰Ca background level of 3 × 10^?14 are achieved.We demonstrate that both systems are well suited for large-scale ⁴¹Ca biomedical applications.     

The exercise renogram and its interpretation

The exercise renogram is a rarely used diagnostic procedure, but it may visualize an exercise-induced change in renal function related to the pathophysiology of essential hypertension, which could greatly increase interest in this examination. The aim of this study was to demonstrate the interpretative approach and the terminology which is used to describe results of exercise renography, using a population of hypertensives with renovascular disease. METHODS: We reviewed the examinations of 70 hypertensives who had supine renography as well as exercise renography with a 60-80 W work load. Forty-eight patients were examined with 99mTc-MAG3 and 22 with 131I hippurate. The renographic and angiography results were recorded as well as the antihypertensive drugs used and the site of vascular lesions. RESULTS: Thirty-three hypertensives developed a bilateral-abnormal exercise renogram, which appears to be associated with primary hypertension. Eight individuals responded to exercise with a unilateral-abnormal exercise renogram, in a kidney behind a stenosis. Only 19 patients had a normal exercise renogram, and 10 had only one functioning kidney. Pathology recognized but unrelated to the intervention included nonfunctioning and small kidneys and pelvic retention. CONCLUSION: Exercise renography's only indication is for recognition of pathology unique to hypertension, since other function disturbances were recognized in resting renograms.