Development of an evaluation methodology for the natural circulation decay heat removal system in a sodium cooled fast reactor

A natural circulation evaluation methodology has been developed to ensure the safety of a sodium-cooled fast reactor (SFR) of 1500 MW adopting the natural circulation decay heat removal system (NC-DHRS). The methodology consists of a one-dimensional safety analysis which can evaluate the core hot spot temperature taking into account the temperature flattening effect in the core, a three-dimensional fluid flow analysis which can evaluate the thermal-hydraulics for local convections and thermal stratifications in the primary system and DHRS, and a statistical safety evaluation method for the hot spot temperature in the core. The safety analysis method and the three-dimensional analysis method have been validated using results of a 1/10 scaled water test simulating the primary system of the SFR and a sodium test simulating a part of the primary system and the DHRS with about a 1/7 scale, and the applicability of the safety analysis for the SFR has been confirmed by comparing with the three-dimensional analysis adopting the turbulence model. Finally, a statistical safety evaluation has been performed for the SFR using the safety analysis method.     

Tangent height registration method for the Version 1.4 data retrieval algorithm of the solar occultation sensor ILAS-II

The Improved Limb Atmospheric Spectrometer-II (ILAS-II) is a satellite-borne solar occultation sensor onboard the Advanced Earth Observing Satellite-II (ADEOS-II). The ILAS-II succeeded the ILAS. The ILAS-II used four grating spectrometers to observe vertical profiles of gas volume mixing ratios of trace constituents and was also equipped with a Sun-edge sensor to determine tangent heights geometrically with high precision. The accuracy of gas volume mixing ratios depends on the accuracy of the tangent height determination. The combination method is a tangent height registration method that was developed to give appropriate tangent heights for the ILAS-II Version 1.4 data retrieval algorithm. This study describes the method used in the ILAS-II Version 1.4 retrieval algorithm to register tangent heights. The root-sum-square total random error is estimated to be 30 m, and the total systematic error is 180 m at an altitude of 30 km. The influence of the tangent height errors on the vertical profiles of gas volume mixing ratios in ILAS-II Version 1.4 is estimated by using the relative difference. The relative difference for each species is within 7% (20%) for an altitude shift of +/-100 m(+/-300 m).     

A novel extraction method of fetal electrocardiogram from the composite abdominal signal

In contrast to the ultrasonic measurement of fetal heart motion, the fetal electrocardiogram (ECG) provides clinically significant information concerning the electrophysiological state of a fetus. In this paper, a novel method for extracting the fetal ECG from abdominal composite signals is proposed. This method consists of the cancellation of the mother's ECG and blind source separation with the reference signal (BSSR). The cancellation of the mother's ECG component was performed by subtracting the linear combination of mutually orthogonal projections of the heart vector. The BSSR is a fixed-point algorithm, the Lagrange function of which includes the higher order cross-correlation between the extracted signal and the reference signal as the cost term rather than a constraint. This realizes the convexity of the Lagrange function in a simple form, which guarantees the convergence of the algorithm. By practical application, the proposed method has been shown to be able to extract the P and T waves in addition to the R wave. The reliability and accuracy of the proposed method was confirmed by comparing the extracted signals with the directly recorded ECG at the second stage of labor. The gestational age-dependency of the physiological parameters of the extracted fetal ECG also coincided well with that of the magnetocardiogram, which proves the clinical applicability of the proposed method.     

Removal of fluoride ions from water by adsorption onto carbonaceous materials produced from coffee grounds

Carbonaceous material for the removal of fluoride ions from water was prepared from coffee grounds (CGs) by calcination and subsequent HCl treatment. The characteristics of the CGs, including the surface area, mean pore diameter, pore volume, and surface functional groups were determined, and the morphological characteristics were evaluated using scanning electron microscopy. The adsorption isotherms, saturated amount of fluoride ions adsorbed, and the effect of contact time and temperature on the adsorption of fluoride ions were investigated for a sample of tap water. The specific surface area of CG calcined at 600° (CG600) was larger than that of CGs calcined at 400, 800, and 1000°. Phenolic, lactonic, and carboxyl groups were detected on the CG600 surface. The adsorption capacity of the carbonized CGs for fluoride was ranked in the order CG400 < CG1000 < CG800 < CG600 (where the numeral indicates the carbonization temperature), whereas virgin CG and CG600-NAT (not treated with hydrochloric acid solution) did not exhibit any adsorption ability for fluoride ions. The amount of fluoride ions adsorbed onto CG600 increased with increasing temperature and was consistent with chemical adsorption. The mechanism of adsorption of fluoride ions onto CG600 proceeded via ion exchange with chloride ions (1:1) present on the surface of CG600. The adsorption isotherms were fitted to the Freundlich and Langmuir equations. Moreover, CG600 showed an acceptable adsorption capacity for fluoride ions present in tap water.     

Operation strategy of residential centralized photovoltaic system in remote areas

Photovoltaic (PV) systems have found fairly wide application in remote isolated area. However, each individual PV system usually supplies energy only to one consumer. In such a case we have several consumers that each one of them uses a stand-alone PV system. This situation would expose such stand-alone systems to transient excessive loads larger than the power generated by the PVs, and then the battery is bound to discharge even during the day. For overcoming this problem, we suggest an autonomous centralized PV system, comprising one battery bank and plural subsystems connected to each other. From solar radiation data and load profiles, the performance of the PV centralized system is simulated by using a time step scheme. The advantages of this system are found to be the large charging rate of power, high efficiency, and low cost compared with conventional individual PV systems and hybrid systems. In addition, the economic study shows that the life cycle cost and the price of kilowatt hour generated in the centralized system is lower than that for the individual systems.     

Evaluation of organ doses in CT examinations with an infant anthropomorphic phantom

The aim of this study is to evaluate organ doses in infant CT examinations with multi-detector row CT scanners. Radiation doses were measured with radiophotoluminescence glass dosemeters set in various organ positions within a 1-y-old child anthropomorphic phantom and organ doses were evaluated from the measurement values. Doses for tissues or organs within the scan range were 28-36 mGy in an infant head CT, 3-11 mGy in a chest CT, 5-11 mGy in an abdominal-pelvic CT and 2-14 mGy in a cardiac CT. The doses varied by the differences in the types of CT scanners and scan parameters used at each medical facility. Compared with those for children of various ages, the doses in an infant CT protocol were found to be similar to or slightly smaller than those in a paediatric CT for 5- or 6-y-old children.     

Fabrication of mesoporous silica KIT-6/polymer composite and its low thermal expansion property

Here we fabricate mesoporous silica KIT-6/epoxy polymer composite as low thermal expansion material. From the specific gravity of the composites, almost all the mesopores (around 90%) are successfully filled with the epoxy polymers. The thermal mobility of the confined polymer molecules inside the mesopores is restricted by the rigid silica frameworks. Therefore, the volume expansion degree of the composites is much lower than that of epoxy polymer. Through the comparative experimental using FSM-16-type mesoporous silica with a 2 dimensional (2D) hexagonal mesostructure, it is proved that KIT-6 system with a 3D bicontinuous gyroid mesostructure more effectively contributes low thermal expansion property.     

Real-time PCB monitoring using time-of-flight mass spectrometry with picosecond laser ionization

The study demonstrates the applicability of laser ionization time-of-flight mass spectrometry for real-time measurement of polychlorinated biphenyls (PCBs). Picosecond 266-nm laser light ionization reduced fragmentation and provided very high PCB detection sensitivity. This high sensitivity has advantages in terms of real-time monitoring capability as compared to the conventional GC-ECD or GC-MS methods, which require at least several days for the analysis of PCBs. Detection sensitivity of under 0.01 mg/Nm3 was achieved with a 1-min measuring time; this sensitivity is superior to the exhaust gas control guideline of 0.15 mg/Nm3 by a factor of 10. A prototype PCB monitoring device has been developed and tested in a pilot PCB treatment plant. The 1-min detection time represents a substantial advance in the monitoring of exhaust gas and the workplace atmosphere in accordance with safety regulations.     

Near-infrared spectroscopic sensing system for online monitoring of milk quality during milking

There has been a need in recent years for a method that will enable dairy farmers to monitor milk quality of individual cow during milking. We constructed a near-infrared (NIR) spectroscopic sensing system for online monitoring of milk quality on an experimental basis. This system enables NIR spectra of unhomogenized milk to be obtained during milking over a wavelength range of 600–1050 nm. We developed calibration models for predicting three major milk constituents (fat, protein and lactose), somatic cell count (SCC) and milk urea nitrogen (MUN) of unhomogenized milk, and we validated the precision and accuracy of the models. The coefficient of determination (r ²) and standard error of prediction (SEP) of the validation set were obtained: for fat, r ² = 0.95, SEP = 0.42%; for protein, r ² = 0.91, SEP = 0.09%; for lactose, r ² = 0.94, SEP = 0.05%; for SCC, r ² = 0.82, SEP = 0.27 log SCC/mL; and for MUN, r ² = 0.90, SEP = 1.33 mg/dL, respectively. These results indicated that the NIR spectroscopic sensing system developed in this study could be used to monitor milk quality in real-time during milking. The system can provide dairy farmers with information on milk quality and physiological condition of each cow and therefore give them feedback control for producing milk of high quality and for optimizing dairy farm management.     

Aquacultural approaches to recycling of dissolved nutrients in secondarily treated domestic wastewaters—III uptake of dissolved heavy metals by artificial food chains

We have studied the biological productivity, measured as biomass yields, of laboratory scale artificial food chains composed of sequential monocultures of suspended unicellular green algae (Scenedesmus), herbivorous cladoceran crustaceans (Daphnia magna), and herbivorous teleost fish (Hypophthalmichthys). These food chains were grown in minimally modified secondarily treated, chlorinated then dechlorinated, domestic waste waters. Successive stages in the chains were fed the organisms grown in the just preceding stages.Additions of 1 ppm ferrous sulfate and aeration with mixtures of air plus 5% carbon dioxide (buffered cultures) increased yields of Scenedesmus cultures by 52% above yields of air aerated, unsupplemented cultures (unbuffered cultures). Buffered cultures remained stable for long periods (1–2 weeks) and maintained good cell quality (no chlorosis; 90+% of cells present were Scenedesmus). Unbuffered, unsupplemented cultures soon became chlorotic, cells autoflocculated (which greatly reduced yields), and changes occurred in species composition. These latter cultures were unsuitable as food for cladocerans.Three production indices (conversion coefficients, specific production, and production/biomass ratios) showed that better growth occurred in cladoceran cultures fed buffered algal cultures as compared with unbuffered cultures. When fed unbuffered cultures cladocerans showed higher production indices when flocculated but unsettled cultures were used, as compared with supernates from flocculated, settled cultures.Attempts to grow the primarily herbivorous silver carp (Hypophthalmichthys molitrix) in a two-stage (buffered algae-fish) food chain failed. Ammonia toxicity may have been the cause of fish deaths.