Performance analysis of self‐excited pulsed MHD power systems

Performance characteristics of self‐excited pulsed MHD power systems are investigated with one‐dimensional time‐dependent calculations using a gas–liquid two‐fluid model. First, the Russian pulsed MHD power system “Pamir‐3U” is analyzed. The result of numerical simulations of hot‐fire tests shows good agreement with the experimental data, confirming the validity of the mathematical model. Performance analysis of Pamir‐3U reveals that the power output is approximately constant with the variation of load resistance, while the ballast resistor consumes a large amount of electric power. It is also shown that the system has been optimally designed to supply a large load current. Next, a new system yielding larger power output is proposed and analyzed. The obtained characteristics show that the new system can provide the maximum power output of 25 MW, which is 10 MW larger than that of Pamir‐3U. © 2000 Scripta Technica, Electr Eng Jpn, 132(3): 30–37, 2000     

Effects of brain lesions on taste-potentiated odor aversion in rats.

Rats failed to acquire aversions to odor stimulus, which was followed 30 min later by an unconditioned stimulus (US). However, when the odor stimulus was accompanied by a taste stimulus, they acquired odor aversions as well as taste aversions. In this phenomenon, referred to as a taste-potentiated odor aversion, lesions of the amygdala disrupted both taste and odor aversions, whereas lesions of the parvicellular part of ventroposteromedial thalamic nucleus (VPMpc) or insular cortex (IC) disrupted taste aversion but attenuated only odor aversion. These results suggest that both taste and odor stimuli are associated with US in the amygdala and that taste inputs delivered to the amygdala through the IC and/or VPMpc play an important role in potentiation of odor aversion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crystal growth of TiAl alloys

The growth of TiAl alloys over a range of Al concentrations has been considered for ingots processed by the floating zone technique. For Al-rich alloys, single crystals of γ-TiAl cannot be grown for compositions below Ti-54 at% Al since a banded microstructure forms due to the limitations imposed by the L + → γ peritectic reaction. However, near stoichemetric TiAl crystals can be grown by the traveling solvent method when using a TiAl---Co flux, although optimum processing conditions have not yet been realized. For Ti-rich alloys, evidence of a growth morphology consisting of β-phase dendrites embedded within a continuous matrix of the peritectic -phase is found for ingots processed up to 200 mm h⁻¹. The final lamellar orientation of the ingot is then determined by the orientation of the peritectic -phase and not by that of the leading β dendrites.     

DEFORMATION BEHAVIOR OF γ-TiAl SINGLE CRYSTALS AT DIFFERENT TEMPERATURES

在－１９６－１１００℃温度范围内,利用压缩试验研究了γ－ＴｉＡｌ单晶（Ａｌ的原子分数为５６％）在「００１」,「１５２」,「０２１」,「２３３」,「１９１」,「２５１」,「１１０」七个晶体取向上的塑性变形行为,它们的屈服强度温度关系曲线都可分成三个部分：－１９６－６００℃屈服强度随温度的升高先是快速下降,达到室温附近以后基本保持不变;６００℃以上,屈服强度随温度的升高而反常升高,随晶体取向的不同在７     

Fabric effect on hydraulic conductivity of kaolin under different chemical and biochemical conditions

A reasonably less permeable compacted clay liner (CCL) is critical to the long-term safety of waste containment facilities. This study experimentally investigates a variety of factors, including salinity, pH, fluctuation in permeant, permeation duration and presence of microorganisms, that are found to influence the hydraulic conductivity (k) of consolidated kaolin and the fabrics of suspended kaolin. Amongst these factors, a reduction in hydraulic conductivity of up to 4 orders of magnitude is obtained from the modification of the microfabrics of kaolin; a reduction of 2 orders of magnitude is brought about by bioclogging; a reduction of 1 order of magnitude is related to the concentrated Ca solution (>10 mM). The hydraulic conductivity of consolidated kaolin can obviously be changed by adjusting the fabrics of the kaolin particles, e.g., clogging the pore spaces with bioslurry, permeating them with alkaline solution, or transforming the kaolin into metakaolin. An effluent pH larger than the isoelectric point (pH_IEP) leads to a rapid reduction in k until 1×10^–11 m/s. A 3-dimensional fabric map was established for kaolin suspension in contact with a wide range of Ca concentrations and pH levels. The fabrics of kaolin suspension are predominated by a salt concentration (C>2.0 mM) and a pH solution (C<2.0 mM), respectively.     

Energetic analysis of SOFC co-generation system integrated with EV charging station installed in multifamily apartment

The authors propose a solid oxide fuel cell (SOFC) co-generation system integrated with an electric vehicle (EV) charging station. To examine the feasibility of the proposed system, the authors numerically simulated the operation pattern of the proposed system, using the electric and thermal demands measured at a multifamily apartment from May 2003 to April 2004. Based on the simulation results, the authors calculated the overall efficiency of the system as well as the primary energy saving rate. The available electric energy for EV charging was also evaluated for the case of the proposed system installed in the multifamily apartment. As a result, it is made clear that the annually averaged overall efficiency reaches about 77% (LHV) and the expected primary energy saving rate exceeds 30% throughout the year. In addition, it is also found that sufficient amount of electric energy for EV charging can be obtained from the proposed system. Therefore, it can be concluded that the proposed SOFC system can successfully combine electrical/thermal energy co-generation and electric vehicle charging while maintaining high energy efficiency and good matching to energy consumption patterns.     

Conceptual design of coupled nonequilibrium disk MHD generator and superconducting magnet system

The authors propose a new conceptual design method for a coupled nonequilibrium disk MHD generator and superconducting magnet system. At first, a generator with constant magnetic flux density is conceptually designed by using the new generator design method recently developed by the authors, and several superconducting magnets suitable for the generator are conceptually designed. Next, considering the obtained magnetic flux density distribution of each magnet, the design calculation of the generator is performed again, and the specifications of the generator are corrected. From the obtained coupled systems, the optimum system is finally selected through synthetical consideration of various requirements. The procedure of the proposed method is very simple, and no iterative calculation is contained in the correction process. Incorporating the new generator design method makes this advantage possible because the generator size can be fixed in the correction process. In the conventional method, a change of magnetic flux density distribution leads directly to a change in the generator size, and therefore, design calculations of the generator and magnet should be iterated in the correction process until they converge to consistent sizes. The procedure of the new conceptual design method is explained in detail by taking the case of a supersonic generator with a caesium seeded helium plasma and 100 MW thermal input.     

Changes in microstructure and absorption-desorption pressures during hydrogen cycling in some intermetallic compounds

Changes in microstructure and their effects on hydrogen sorption properties have been investigated as a function of the number of hydrogen sorption cycles in LaNi₅ and FeTi. For LaNi₅, while the desorption pressure does not significandy depend on the number of cycles, the absorption pressure drastically decreases between the first and second cycles. In addition to severe cracking and pulverization, numerous edge dislocations with Burgers vectors of the l/3<1210>-type are introduced during the first absorption cycles. Both the introduction of numerous lattice defects and the formation of severe cracks seem to be completed during the first cycle, resulting in the reproducible P (pressure)-C (composition) characteristics for the subsequent cycles. In contrast, FeTi exhibits ever-changing P-C characteristics with cycle number. The introduction of dislocations with Burgers vectors of the <100>-type in the form of tangles and cracks occurs during each of absorption cycles with the extent to which this occurs being considerably smaller in each of absorption cycles of FeTi than in the first absorption cycle of LaNi₅. The difference in material response to hydrogénation seems to be closely related to the difference in ductility of these two intermetallics.     

Bacterial phosphotransferase system (PTS) in carbohydrate uptake and control of carbon metabolism

More than 20 carbohydrates may be transported into the bacterial cell by the phosphoenopyruvate:carbohydrate phosphotransferase system (PTS) that is widely spread among bacteria. The PTS consists of two cytoplasmic energy-coupling proteins (Enzyme I and HPr) and a range of carbohydrate-specific Enzymes II, which catalyze concomitant carbohydrate translocation and phosphorylation. The phosphorylation status of PTS components reflects the availability of carbohydrates and the energy conditions of the cell. In many bacteria, PTS and the associated proteins convert this information to signals, which transduced through different mechanisms lead to phenomena of catabolite repression, inducer control or chemotaxis. These features of PTS provide bacteria with an integrated system, which assures optimal utilization of carbohydrates in complex environments. Furthermore, some bacteria evolved parallel systems that serve a regulatory functions, but apparently do not catalyze the carbohydrate transport. Here we review the findings that recently advanced the understanding of various aspects of PTS-dependent carbohydrate transport and regulation of bacterial catabolism.     

Plastic deformation of single crystals of VSi2 and TaSi2 with the C40 structure

The deformation behavior of (0001)110 basal slip in single crystals of VSi₂ and TaSi₂ with the C40 structure has been investigated in the temperature range from room temperature to 1500 °C in compression. Plastic flow is observed only above 400 and 600 °C for VSi₂ and TaSi₂, respectively. The critical resolved shear stress (CRSS) for basal slip decreases with increasing temperature but exhibits a moderate peak around 1100 and 1400 °C for VSi₂ and TaSi₂ respectively. Dislocations with b = 1/3110 gliding on (0001) basal planes both in VSi₂ and in TaSi₂ are observed to dissociate into two identical partials with b = 1/6110 involving a stacking fault. High-resolution transmission electron microscopy of 1/3110 dislocations indicates that basal slip both in VSi₂ and in TaSi₂ occurs through a conventional single shearing mechanism, unlike in isostructural CrSi₂ and Mo(Si,Al)₂ in which basal slip occurs through a synchroshear mechanism.