Vibrations of probe used for the defect detection of helical heating tubes in a fast breeder reactor: Part 2. Vibration analysis and numerical simulations

A detection of a defect of a helical heating tube installed in the fast breeder reactor “Monju” in Japan is done by a feeding of an eddy current testing (ECT) probe with magnetic sensor into the tube. An undesirable vibration of the ECT probe always happens under a certain condition and makes the inspection difficult. Several characteristics of the vibration have been made clear by some experiments using a mock-up, but the essential factor of the vibration is still unclear. In this paper, a numerical simulation of the vibration is implemented on the assumption that the vibration is caused by Coulomb friction. An analytical model, which is obtained as a lumped mass model, is a large-scale non-linear vibration system and many computational costs are ordinarily required to carry out the simulations. The Transfer Influence Coefficient Method is applied so that the simulation is efficiently carried out. The results of simulation qualitatively agree well with the experimental results. It confirms the validity of the assumption that the vibration is caused by Coulomb friction.     

Thermodynamic properties of neptunium nitride: a first principles study

The thermal and mechanical properties of neptunium nitride (NpN) were investigated by first principles calculations. From the Helmholtz free energy equilibrium lattice constants, thermal expansion coefficients, bulk moduli and specific heat capacities were calculated for temperatures up to 1500 K. The electronic specific heat capacity was also calculated from the electronic density of states at the Fermi energy. The obtained specific heat capacity reproduced the experimental data well. It was thus clarified that the specific heat capacity of NpN consists of the lattice and electronic specific heat capacities and the contribution of the lattice dilatation to the specific heat capacity.     

Development of technology for recovering lithium from seawater by electrodialysis using ionic liquid membrane

Tritium fuel for fusion reactors is produced by reacting lithium-6 (⁶Li) with neutrons in tritium breeders. This study demonstrates a method for Li recovery from seawater, wherein Li does not permeate from the anode side to the cathode side through an ionic liquid N,N,N-trimethyl-N-propylammonium–bis(trifluoromethanesulfonyl) imide. Almost all Li ions remain on the anode side (seawater), whereas the other ions in the seawater permeate to the cathode side through the ionic liquid with an applied electric voltage of 2–3 V.     

16-channel optical FDM distribution/transmission experiment utilising Er/sup 3+/-doped fibre amplifier

A 16-channel optical FDM distribution/transmission experiment at around 1534 nm wavelength is demonstrated utilising an Er/sup 3+/-doped fibre amplifier. 16 intensity-modulated optical signals at 622 Mbit/s were amplified simultaneously at a gain of 15.2-18.5 dB. One of the amplified signals is selected using the waveguide frequency selection switch and directly detected with a receiver sensitivity of -38 dBm (P/sub e/=10/sup -9/).<>     

Wavelength conversion with self wavelength selection using Mach-Zehnder filter and DFB-LD

Wavelength conversion with a self wavelength selecting function is described. The convertor utilises the FM/IM conversion function of a Mach-Zehnder filter and the light injection induced frequency shift in a DFB laser diode. Frequency-modulated light is converted to another wavelength which can be tuned by a wavelength selection signal contained in the original input light.<>     

Development of Radiation Hard ${rm N}^{+}$-on-P Silicon Microstrip Sensors for Super LHC

Radiation tolerance up to 10¹⁵ 1-MeV n_eq/cm² is required for the silicon microstrip sensors to be operated at the Super LHC experiment. As a candidate for such sensors, we are investigating non-inverting n⁺-on-p sensors. We manufactured sample sensors of 1 times 1 cm in 4" and 6" processes with implementing different interstrip electrical isolation structures. Industrial high resistive p-type wafers from FZ and MCZ growth are tested. They are different in crystal orientations lang100rang and lang111rang with different wafer resistivities. The sensors were irradiated with 70-MeV protons and characterized in views of the leakage current increase, noise figures, electrical strip isolation, full depletion voltage evolution, and charge collection efficiency.     

亲肿瘤显像剂5-18F-Fluorouracil(18F-FU)的标记合成研究

用^18/F2Uracil直接标记法合成了5－^18F-Fluorouracil,探索^18F-FU-PET显像对结肠直肠肝转移病人化疗前后疗效评价的意义。产品的放射化学纯＞95％,放射性得率为60％,pH值为7,无菌性试验和热源性试验为阴性,这一结果为临床应用提供了保证。     

Self—Induced Oscillation of Supersonic Jet During Impingement on Cylindrical Body

INTaoDUCTIONThephenomenaoftheinteractionbetweenthesu-personicjetandanobstaclearerelatedtotheproblemSoftheaeronauticalengineeringsuchasthedesignoftherocketlaunchersysteml1]andillterestinginrela-tiontotheindustrialengineerings.Thefiowisshowntobethehsocomplexthreedimensionalwavpat-terncolit~shodwavesduetotheimpingemelltofasuPersonicjetonanobstacle,ManystudiesontheinteractionbrtweenthesuPersonicjetandanobstaclehavebeenreportedconcerningtheinteractionsoftheshodwaves[l]-I5l,theflowcharacteristi…     

Biohydrogen production from cassava starch processing wastewater by thermophilic mixed cultures

Natural microbial consortia from hot spring samples were used to developed thermophilic mixed cultures for biohydrogen production from cassava starch processing wastewater (CSPW). Significant hydrogen production potentials were obtained from three thermophilic mixed cultures namely PK, SW and PR with maximum hydrogen production yields of 249.3, 180 and 124.9 mL H₂/g starch, respectively from raw cassava starch and 252.4, 224.4 and 165.4 mL H₂/g starch, respectively from gelatinized cassava starch. Acetic acid-ethanol and acetic-lactic acid type fermentation were observed in cassava starch fermentation, based on three thermophilic mixed cultures performance. The thermophilic mixed cultures PK, SW and PR exhibited the maximum hydrogen yield of 287, 264 and 232 mL H₂/g starch in CSPW, respectively corresponding to 53%, 48.7% and 42.8% of the theoretical values. Phylogenetic analysis of thermophilic mixed cultures revealed that members involved cassava starch degrading bacteria and hydrogen producers in both raw cassava starch and CSPW were phylogenetically related to the Thermoanaerobacterium saccharolyticum, Thermoanaerobacterium thermosaccharolyticum, Anoxybacillus sp., Geobacillus sp. and Clostridium sp.     

Effect of conditioning method on direct methanol fuel cell performance

We investigated the effect of the conditioning methods on improving the direct methanol fuel cell (DMFC) performance. The DMFC performance after the conditioning was measured using a newly developed single cell having an Ag/Ag₂SO₄ reference electrode, which is not influenced by methanol. As a result, we succeeded in developing an original two-step conditioning method in which the conditioning by fueling H₂ gas is conducted prior to a conventional DMFC conditioning. The anode and cathode characteristics after the two-step conditioning were measured with respect to a reference electrode. Based on the obtained i-E curves, the two-step conditioning is found to improve the methanol oxidation performance at the anode and also suppress the decline of the O₂ reduction performance at the cathode. The high DMFC performance based on the two-step conditioning is well explained by the anode and cathode characteristics.