Optimization of the PGV-1000MKO Steam Generator Using CFD

In the VVER -TOI project, new layout solutions were applied in the reactor plant as part of which the steam removal system from the steam generator was changed. Namely, in contrast to the VVER-1000 and VVER-1200 where the steam removal was organized through ten nozzles combined into a steam collector, in the VVER -TOI SG the steam removal was arranged through one nozzle located on the cold collector side. This change leads to the formation of a non-uniform velocity field in the separation volume. To ensure the steam separation characteristics of a horizontal steam generator with one steam nozzle, it was proposed to create a non-uniform resistance on the way of steam motion from the evaporation surface into steam nozzle applying a non-uniform degree of the distribution perforated plate (DPP) perforation. Two computer models of the SG steam volume with different steam removal schemes (one and ten nozzles) were developed, a set of studies on verification and validation was carried out and a set of calculations were performed. Further, to determine the non-uniform degree of DPP perforation, a set of optimization calculations of the SG steam volume with one steam removal nozzle was performed. The non-uniform degree of DPP perforation of the VVER-TOI SG was selected, which provide steam velocity distribution as close as possible to SG with ten steam nozzles. To justify the chosen design, sensitivity analysis was also carried out according to the hole diameters tolerance and steam load profile.

Modeling and Analysis of the Steering Resistance Moment in Small Tracked Robot

A modeling method for steering resistance moment in small tracked robot is studied. First of all, Classical steering resistance torque modeling with uniform resistance is studied in low speed and high speed. Then the steering resistance torque modeling while lateral resistance and the pressure are linearly distributed is proposed. After that steering resistance moment modeling based on the stress-strain theory is used to describe the robot's steering resistance above different soil. Among them, the lateral resistance is nonlinear distribution. The driving experiments in three different vehicle terramechanics models are simulated and analyzed. Steering resistance moment modeling based on the stress-strain theory is closer to the actual working state of the robot. This modeling method for steering resistance moment has advantage on optimization and study in and control algorithm.

Recovery and Sporicidal Resistance of Various B. subtilis Spore Preparations on Porcelain Penicylinders Compared with Results from AOAC Test Methods

Sporicidal test results obtained from carriers inoculated with 4 types of defined Bacillus subtilis spore preparations were compared with the standard AOAC sporicidal test using soil extract nutrient broth (SENB) B. subtilis 19659 spores. Recoveries of spores inoculated on penicylinders from B. subtilis clean spores (washed and suspended in water) and B. subtilis 19659 spores inoculated from culture filtrates according to the AOAC method were compared. Spores were exposed to 6 concentrations (0.5–3.0% w/v) of glutaraldehyde in phosphate buffer (pH 7.5) for 10 h. Concentrations were established by titrimetry and liquid chromatography. Recoveries of surviving spores were determined for 3 types of clean B. subtilis var. niger preparations, one clean B. subtilis 19659 preparation, and the SENB B. subtilis 19659 filtrates. Spore carriers, inoculated by the standard AOAC protocol, resulted in as much as a 2-log number difference in runs 1–12, but not more than 0.5 log number for each clean spore preparation. The SENB spores varied most in resistance to glutaraldehyde, with no growth in recovery media from 3 different batches of 1, 1.5, and 2% glutaraldehyde. Separate batches of SENB preparations of B. subtilis 19659 were resistant and destroyed by 1.0% glutaraldehyde, with 3.98 and 6.0 log numbers of spores on penicylinders, respectively. Clean spore preparations of B. subtilis 19659 on porcelain penicylinders were more resistant to glutaraldehyde than were SENB spores. Nutrient agar/Mg/Ca and nutrient agar/Mg spore preparations of B. subtilis var. niger showed the most uniform resistance to glutaraldehyde. Spores with calcium added showed increased resistance to glutaraldehyde. B. subtilis 19659 spores from the Columbia broth spore preparation were the most resistant and were recovered after exposure to 3.0% glutaraldehyde.

Resistance in Twenty-two Cultivars of Spathiphyllum to Cylindrocladium Root Rot

Twenty-two spathiphyllum cultivars were evaluated for resistance to Cylindrocladium root rot (CRR). Four isolates of the fungus Cylindrocladium spathiphylli Shoult., El-Gholl & Alf. were selected from two different locations each in Florida and Hawaii. Spores of isolates were applied as a soil drench in replicated experiments using a randomized complete block design. The most severe symptoms were those produced by C. spathiphylli isolates from Hawaii. None of the spathiphyllum cultivars tested were highly resistant to CRR although resistance among the cultivars was observed. The cultivars Chris and Textura were the most promising cultivars, having fairly uniform resistance to the four isolates of C. spathiphylli. The cultivars Cupido, Daniel, Frederik, Jetty, and Vanessa were moderately resistant when combined data from all tests were analyzed. Results from this research permit the selection of more resistant breeding lines and also creates a baseline against which resistance of newly developed cultivars can be compared.

Combating Heart Disease with FEA

Biomedical researchers are combining electrostatic finite element analysis (FEA) software with laboratory testing to improve treatments for arrhythmia. The researchers used Algor's Superdraw Ill, a precision finite-element model-building tool, to model a 100-by-100-centimeter sheet, which represented a conductive area of the heart. They applied a resistivity value based on a thickness of 1cm to simulate a uniform resistance over heart fibers. The finite element model showed that current through the element faces at the ends of the electrodes was 151 percent larger than current near the electrode center. The researchers also used FEA to determine that the length of the line electrode does not affect the current distribution. In order to confirm the results of the analysis and further test the positioning of the electrode with respect to heart fibers, researchers applied line electrodes in varying positions andorientations on 13 hearts from New Zealand rabbits. Finally, researchers could determine the distribution of the change in transmembrane voltage from a line electrode, made up of a summation of points, using electrostatic analysis.