Analysis of the turbine deblading in an HTGR with the CATHARE code

The direct coupling of a Gas Cooled Reactor (GCR) with a closed gas-turbine cycle leads to a specific dynamic plant behaviour. This behaviour is described and illustrated through computer analyses performed at CEA with the computer code CATHARE. This analysis requires a 1D code able to simulate the whole reactor, including the core, the vessel, the piping and the components (turbine, compressors, heat exchangers).This paper is devoted to deblading accidents. The problems and solutions encountered in various types of gas-turbines are presented: aero engines, steam turbines (EDF-Porcheville steam turbine accident feedback) and finally the feedback from previous High Temperature Gas Reactor experiments (EVO helium loop, HHT project and other HTR projects) are displayed. From this literature survey, some recommendations are drawn for a future High Temperature Reactor. It is shown that for safety reasons in case of deblading, a horizontal shaft aligned with the reactor vessel is recommended for the turbomachinery.This paper presents simulations of different scenarii performed with CATHARE code:

(a) Turbine deblading with and without reactor trip. In these calculations, a pessimistic assumption has been made: all turbine blades break off.

(b) Total flow blockage. The flow area is entirely blocked by the turbine blades.

(c) Partial flow blockage. Previous conclusions consider the worst cases of deblading and total flow blockage. An intermediate case based on a partial deblading has also been performed.

CATHARE results illustrate that the loss of turbine blades is accompanied by abrupt changes in the Power Conversion System and reactor flow conditions: large axial pressure drop, reverse flow through the core and high rate de-pressurization.     

Stimulatory effect of follicle-stimulating hormone on basal and luteinizing hormone-stimulated testosterone secretions by the fetal rat testis in vitro

The in vitro effect of FSH on testosterone secretion by the fetal rat testis was studied. Testes were cultured in the presence or absence of either commercial human (h) FSH (Metrodine; 200 mIU/ml) or recombinant hFSH (200 mIU/ml) for 3 days and with 100 ng/ml ovine LH during the last 4 h of culture. To avoid a stimulatory effect by the 0.4% LH that contaminates Metrodine, the cultures were performed in the presence of a monoclonal anti-hLH beta antibody and with a concentration of Metrodine that had no short term stimulatory effect on testosterone production by the fetal testes in vitro. Metrodine treatment had a positive long term effect on both basal and LH-stimulated testosterone secretion by fetal testes explanted on days 18.5, 20.5, and 22.5 postconception, which was abolished by the addition of a monoclonal anti-hFSH beta antibody. LH-free recombinant FSH also augmented basal and LH-stimulated testosterone secretion of testes explanted on days 13.5, 14.5, and 18.5 postconception. The positive effect of recombinant hFSH appeared during the second day of treatment with day 14.5 and 18.5 testes and on the third day of treatment with day 13.5 testes. As it is widely accepted that FSH receptors are exclusively localized on Sertoli cells, these results suggest that on or before day 15.5 of fetal life, 1) Sertoli cells are able to respond to FSH, 2) Sertoli cells can produce factors that are able to act on Leydig cell function, and 3) Leydig cells are sensitive to FSH-induced Sertoli cell factors. In conclusion, this study points out a potential paracrine control of fetal Leydig cell function and/or differentiation by fetal Sertoli cells as soon as fetal Leydig cells differentiate.     

Renal duplex scanning: correlation with angiography and isotopic renography

The purpose of this study was to assess the accuracy of Duplex scanning in detecting renovascular disease and to compare it with angiography, renal scintigraphy and captopril test for plasma renin activity and isotopic renography. A Duplex scan was performed in 92 renal arteries (46 patients) and compared to angiography. Three degrees of stenoses were established: 0-60%, 61-99% and occlusion. The peak systolic velocity (PSV) in the renal artery and its ratio to the peak velocity in the aorta (RAR) were used to discriminate stenoses > 60%. PSV in the interlobar arteries was used to assess the relative perfusion of both parenchyma. Angiography demonstrated a stenoses > 60% in 23 hypertensive patients. In all of the patients, plasma renin activity was measured and isotopic renograms (pre- and post-captopril) obtained in order to discriminate hypertension of vascular origin. A PSV in the renal artery > 210 cm/s and a RAR > 3.5 were found to be the diagnostic criteria with the best sensitivity and specificity in detecting stenoses > 60%. Based on these data, Duplex correctly identified 49/54 stenoses > 60%; 28/33 stenoses < 60%; and 5/5 occlusions (kappa 0.79). Sensitivity and specificity in detecting stenoses > 60% were 89.5 and 90.7%, respectively. The ratio between PSV in the interlobar arteries of both parenchyma accurately predicted the relative perfusion (ratio between DTPA uptake in both kidneys) in the isotopic test (n = 23, r = 0.91, p = 0.001). The captopril test (for plasma renin activity and isotopic renography) was positive in only five patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Liquid chromatographic determination of five benzoylurea insecticides in fruit and vegetables

A liquid chromatographic (LC) method was developed to determine 5 benzoylureas--diflubenzuron, hexaflumuron, teflubenzuron, flufenozuron, and lufenuron--in peppers, tomatoes, eggplants, cucumbers, and oranges. Preparation of samples involve extraction with acetone and partitioning into dichloromethane-petroleum ether. A portion of this extract is cleaned up with a solid-phase extraction aminopropyl disposable column. With LC analysis using an RP-8-DB microbore column, acetonitrile-water (70 + 30, v/v) as mobile phase, and photodiode array detection at 254 nm, recovery and repeatability data were collected for the 5 benzoylureas on 4 vegetables and citrus in the range 0.04-2.0 mg/kg. Validated limits of detection and quantitation were 0.01 and 0.04 mg/kg, respectively. The method is reliable for routine analysis of vegetables and fruits.     

Early bankruptcy prediction using ENPC

Bankruptcy prediction has long time been an active research field in finance. One of the main approaches to this issue is dealing with it as a classification problem. Among the range of instruments available, we focus our attention on the Evolutionary Nearest Neighbor Classifier (ENPC). In this work we assess the performance of the ENPC comparing it to six alternatives. The results suggest that this algorithm might be considered a good choice.     

Performance of the most common non‐cryptographic hash functions

Non‐cryptographic hash functions (NCHFs) have an immense number of applications, ranging from compilers and databases to videogames and computer networks. Some of the most important NCHF have been used by major corporations in commercial products. This practical success demonstrates the ability of hashing systems to provide extremely efficient searches over unsorted sets. However, very little research has been devoted to the experimental evaluation of these functions. Therefore, we evaluated the most widely used NCHF using four criteria as follows: collision resistance, distribution of outputs, avalanche effect, and speed. We identified their strengths and weaknesses and found significant flaws in some cases. We also discuss our conclusions regarding general hashing considerations such as selection of the compression map. Our results should assist practitioners and engineers in making more informed choices regarding which function to use for a particular problem. Copyright © 2013 John Wiley & Sons, Ltd.     

Removal of lindane using electrokinetic soil flushing coupled with air stripping

Journal of Applied Electrochemistry - This paper evaluates the remediation of soil spiked with lindane using a combined treatment consisting of electrokinetic soil flushing (EKSF) with air...