Thermal hydraulic analysis compared with tests of full-scale concrete casks

To develop a thermal analysis method for the concrete cask, numerical calculation based on thermal hydraulic phenomena was performed. In the present calculation model, calculation area was divided into two parts. One is inside of the canister and the other is outside of the canister. These two parts were combined at the surface of the canister. In the model of the outside, k– turbulence model was adopted for air flow region. Comparing calculation results with test results, it was found that the analysis method was valid for normal and accident conditions of the storage.     

Development of monitoring technique for the confirmation of spent fuel integrity during storage

A method is developed to monitor integrity of spent fuels stored in a canister that is sealed by weld. To achieve the monitoring, Kr-85 gas was newly adopted as a kind of probe. In the case of a fuel rod defect, Kr-85 gas of the fuel rod is leaked in the canister. By detection of gamma ray (514 keV) emitted from Kr-85 outside of the canister, defected rods can be detected without unsealing the canister. The monitoring technique was developed using small-scaled mock-up experiments and simulated calculation. The result showed that Kr-85 gas leakage of about 10¹¹ Bq is detectable under the noise gamma rays by using the detection system with collimator, which is about 10% of Kr-85 inventory in a fuel rod. Therefore, this monitoring technique is considered as an inspection method prior to transportation of spent fuel from an interim storage facility to a reprocessing plant.     

Trends in research foci in life science fields over the last 30 years monitored by emerging topics

We report here a simple method to identify the ‘emerging topics’ in life sciences. First, the keywords selected from MeSH terms on PubMed by filtering the terms based on their increment rate of the appearance, and, then, were sorted into groups dealing with the same topics by ‘co-word’ analysis. These topics were defined as ‘emerging topics’. The survey of the emerging keywords with high increment rates of appearance between 1972 to 2006 showed that emerging topics changed dramatically year by year, and that the major shift of the topics occurred in the late 90s; the topics that cover technical and conceptual aspects in molecular biology to the more systematic ‘-omics’-related and nanoscience-related aspects. We further investigated trends in emerging topics within various sub-fields in the life sciences.     

Pulse Combustors—Performance and Control

Limited resources of fossil energy require the search for new energy conversion processes and the increase of the efficiency of power plants to ensure the energy household in the future. Basically, changing the combustion mode from steady to pulse combustion makes an enormous reduction of fuel consumption possible. Active control systems for pulse combustors installed into the inlet further improve the efficiency and extend the operating range considerably. The control algorithm including fuel rate - air rate - pressure characteristics and control strategies as well are presented.     

Partial oxidation of n-hexadecane and polyethylene in supercritical water

In this study, we show the results of partial oxidation experiments of n-hexadecane (n-C₁₆) and polyethylene (PE) in supercritical water (SCW). The experiments were carried out at 673 or 693 K of reaction temperature and 5 or 30 min of reaction time using a 6 cm³ of a batch type reactor. Water density ranged from 0.1 to 0.52 g/cm³ (water pressure: 20–40 MPa). The loaded amount of oxygen was set to 0.3 of the ratio of oxygen atom to carbon atom. Some experiments were made using CO instead of oxygen for the partial oxidation of n-C₁₆ and PE to explore the effect of water gas shift reaction. In the results of partial oxidation of n-C₁₆, the yield of CO and some compounds containing oxygen atoms, such as aldehydes and ketones increased with increasing water density. Moreover, 1-alkene/ n-alkane ratio in the products decreased with increasing water density. The 1-alkene/n-alkane ratio was lower than that of pyrolysis in SCW. Also for the case of PE experiments, in dense SCW (0.42 g/cm³), the 1-alkene/n-alkane ratio in partial oxidation was lower than that in SCW pyrolysis. In the case of CO experiments for n-C₁₆ and PE, 1-alkene/n-alkane ratio was a little lower than that of pyrolysis in SCW. These results show that the yield of n-alkane, which is a hydrogenated compound, was higher through water gas shift reaction in SCW and also through partial oxidation in SCW. Therefore, these results suggest the possibility of hydrogenation of hydrocarbon through partial oxidation followed by the water gas shift reaction.     

An FPGA implementation of real-time K-means clustering for color images

K-means clustering is a very popular clustering technique, which is used in numerous applications. In the k-means clustering algorithm, each point in the dataset is assigned to the nearest cluster by calculating the distances from each point to the cluster centers. The computation of these distances is a very time-consuming task, particularly for large dataset and large number of clusters. In order to achieve high performance, we need to reduce the number of the distance calculations for each point efficiently. In this paper, we describe an FPGA implementation of k-means clustering for color images based on the filtering algorithm. In our implementation, when calculating the distances for each point, clusters which are apparently not closer to the point than other clusters are filtered out using kd-trees which are dynamically generated on the FPGA in each iteration of k-means clustering. The performance of our system for 512 × 512 and 640 × 480  pixel images (24-bit full color RGB) is more than 30 fps, and 20–30 fps for 756 × 512 pixel images in average when dividing to 256 clusters.

Electromagnetic shielding property of laminated carbon fiber tape reinforced thermoplastics

ABSTRACT

Carbon fiber reinforced thermoplastic (CFRTP) has a good electromagnetic shielding property due to its higher conductivity and broad absorption frequency bandwidth while presenting high specific strength and stiffness, their easy process-ability, cost-effectiveness, and recyclability. In the present study, laminated CFRTP made of carbon fiber-polyamide 6 unidirectional tape (UD tape) were fabricated with different laminate configurations and arrangements (unidirectional, bidirectional, and quasi–isotropic) and then were compared with randomly chopped-tape CFRTP. Thereafter, estimated electromagnetic interference shielding effectiveness (EMI-SE) using Simon formalism and flexural properties of CFRTP were evaluated. The result showed a remarkable total EMI-SE of 31–44 dB in the Ultra High Frequency (UHF) range and strongly correlated with the laminate configuration of CFRTP. Whereas, randomly chopped-tape CFRTP has a lower total EMI-SE of 23–27 dB in the same frequency range. In addition, the flexural test result showed the flexural strength and modulus are strongly influenced by the tape layer configuration in the laminated CFRTP. Moreover, microscopy analysis was also conducted to verify the interlaminar structure and fiber-to-fiber contact in the composite. In conclusion, laminated CFRTP made of UD tape can be considered as electromagnetic interference shielding material for both functional and structural applications.     

Effect of chlorphentermine on incorporation of [14C]choline in the rat lung phospholipids

The effect of chlorphentermine (CP) treatment (50 mg/kg/ day, per os [po]) on the incorporation of [¹⁴C]choline into rat lung phospholipid was studied.Total phospholipid content was increased 2.0-fold and 1.7-fold after seven and 14 days, respectively, compared with the pair-fed rats. The incorporation of [¹⁴C]choline into phosphatidylcholine (PC) was significantly inhibited by either seven or 14 days of CP treatment. Nevertheless, the PC content was significantly increased by day 7 and stayed elevated at day 14 of CP treatment. Choline and phosphorylcholine contents were significantly decreased by the CP treatment. These results suggest that the higher accumulation of PC is due to inhibition of enzymes involved in the hydrolysis of phospholipids rather than to a stimulation of the phospholipid synthesis. Presented in part at the SOT Meeting, Atlanta, GA, March 1984 (abstracted inThe Toxicologist 4[1], 64).