Correlation study between hydrogen absorption property and lattice structure of Mg-based BCC alloys

Nanostructured Mg₆₀Ni₅Co_mX_35 − m (X = Co, B, Al, Cr, V, Pd and Cu) body centered cubic (BCC) alloys were synthesized by mechanical alloying method. These Mg-based alloys with different lattice parameters can show significantly different hydrogen absorption properties. The BCC alloys with lattice parameter in the range of 0.300∼0.308 nm absorb large amount of hydrogen at 373 K and the BCC alloys with the parameter larger than 0.313 nm have difficulty to absorb hydrogen at this temperature. Geometric effect is thought to be one of the dominant factors to affect the hydrogen absorption property of interstitial alloys. Nanostructure, fresh surface area and defects produced during mechanical alloying process are also important facts that make Mg-based alloys absorb hydrogen at 373 K.     

Synthesis of Mg2FeD6 under low pressure conditions for Mg2FeH6 hydrogen storage studies

Mg₂FeD₆ is successfully synthesised with various degrees of purity using reactive ball milling and annealing under low pressure deuterium conditions to a maximum of 10 bar. The deuteride of the low cost ternary metal hydride Mg₂FeH₆, is synthesised to enable further characterisation studies such as isotopic exchange behaviour. Both on laboratory and industrial scales, keeping the pressure low reduces the need for expensive compression systems and also minimises the quantity of gas necessary for use; therefore it is important to assess synthesis under these cost effective conditions. This is especially the case when using a specialised gas such as high purity deuterium. The maximum pressure chosen is 10 bar, to comply with the High Pressure Safety Act in Japan. This Safety Act limits the use of any gas including hydrogen and deuterium to 10 bar eliminating the use of traditional synthesis methods for Mg₂FeH₆ or Mg₂FeD₆ synthesis at high pressure (120 bar). Ball milling parameters such as milling times, ball to powder ratios as well as sintering times were altered to achieve improved Mg₂FeD₆ yields under these low pressure conditions.     

Transient rolling behaviour of a slider supported by two rollers

A rolling element has a spring characteristic in the transient displacement region from the stationary state to a continuous rolling motion. For this reason, a bearing having a rolling element is useful for constructing an ultra-precision positioning device. In this paper, a mechanism for the damping capacity generation of a rolling element is investigated, to improve the dynamic characteristic of this positioning device. A stage supported by two rollers is constructed, and its tangential displacement is measured accurately when the driving force is acting. As a result, it is confirmed that the rolling element has a nonlinear spring characteristic. Energy loss is generated by the reciprocating motion of the stage in the transient displacement region. This is the main cause of the damping capacity. Furthermore, this energy loss or damping capacity of the stage can be improved by using two rollers with different diameters.     

A compact three-dimensional packaging technique usingsuper-fine-pitch coaxial connector arrays for on-board satelliteequipment

A compact three-dimensional (3-D) inter-module microwave packaging technique has been developed that drastically reduces the volume of on-board satellite equipment of phased-array beam control (PBC). A super-fine-pitch coaxial connector (SCC) array has been successfully implemented with this 3-D structure along with very flat, superior-performance ceramic MMIC packages and combiner packages. Two types of SCC have been developed-a lead-to-jack array and a plug-to-plug array-both of which have a 2-mm pin pitch. Through application of this 3-D packaging technique to S-band 61-beam 32-radiator PBC equipment, an ultra-small packaging unit was developed that houses a 32×64 interconnection in a 2600-cc chassis. This technique promises to make possible compact, light-weight on-board PBC equipment that is especially suitable for use in satellite transponders     

A large generator's bids in an electricity supply auction: Uniform pricing versus pay‐as‐bid pricing

A pay‐as‐bid auction has been adopted in a balancing market under New Electricity Trading Arrangements in England and Wales since 2001 instead of a uniform price auction previously used in a day‐ahead pool market. In contrast, a spot market in Japan, where a general electric utility would be the main supplier, plans to employ a uniform price auction. In this paper we model an electricity spot market in which one large generator competes with many fringe generators to supply electricity, analyze how this large generator bids to maximize its profits, and report some implications for the design of this market. Three types of auction are analyzed: a highest‐winning‐bid pricing (HWB) uniform price auction, a lowest‐losing‐bid pricing (LLB) uniform price auction, and a pay‐as‐bid auction. It is shown that the slope of the bid curve, which is obtained by plotting the large generator's bidding prices against its generation costs, are steeper in an LLB uniform price auction and flatter in a pay‐as‐bid auction than those in an HWB uniform price auction. This implies that an LLB uniform price auction or a pay‐as‐bid auction would make room for the fringe generators to win an auction. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 41–48, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20420     

Plate insertion as a means to improve the damping capacity of a cutting tool system

Effective chatter prevention during cutting operations is achieved by increasing the damping capacity of a cutting tool system. It is well known that damping capacity is generated through (i) micro-slip at the interface between the tool shank and tool post, (ii) slip at the grain boundary within a vibrating body (that is, internal friction), and (iii) friction between the surface of the vibrating body and the surrounding air. Among these three causes of damping capacity, micro-slip at the interface between the tool shank and tool post is the greatest factor affecting the damping capacity of the cutting tool system. In the research investigation, it is shown that the damping capacity of a cutting tool system is improved by friction acting between the inner wall of a rectangular hole made at the overhanging shank of the cutting tool system and the surface of a plate inserted into this rectangular hole. The damping capacity improvement proposed in this paper is realized by a mechanism similar to the inner friction mechanism.     

Dynamics of antioxidant action of vitamin E

Vitamin E is the major lipophilic, radical-scavenging antioxidant in vivo and protects humans from the oxidative stress mediated by active oxygen and nitrogen species. The mechanisms of the inhibition of oxidation by vitamin E in vitro are now fairly well understood, but the dynamics of antioxidant action of vitamin E in vivo have not been well elucidated yet, primarily because of the inherent heterogeneity of biological systems. In this Account, the factors which determine the antioxidant capacity of vitamin E are discussed, and the importance of its localization and mobility in the membranes and lipoproteins is emphasized.     

5%乙烯-醋酸乙烯共聚物复合低热水泥浆体的碳化促进养护

采用碳化养护方法促进5%乙烯-醋酸乙烯共聚物复合低热水泥浆体的水化.通过X射线衍射定性及定量分析测定了养护后样品的组成及水泥中硅酸三钙(3CaO·SiO2,C3S)、硅酸二钙(2CaO·SiO2,C2S)的水化率;利用带固体样品测试装置的全有机碳素分析仪测定了样品所吸收的CO2量;采用水银压入法检测了样品的孔径分布.结果显示:碳化养护大大促进了低热水泥的水化,并有球霰石生成.样品中的总孔隙体积也明显减少,但有大量较大孔径的毛细孔隙存在.碳化养护前,对样品进行水中预养护可以减少这些毛细孔隙,但不利于水泥的水化并导致CO2吸收量及抗折强度显著降低.     

Oxidative degradation of polyolefins. I. Thermal oxidative degradation of atactic polypropylene in solution

Atactic polypropylene was oxidized in solution with radical initiator in the absence and presence of metal catalyst to considerably high conversion over the temperature range of 70° to 125°C, and oxidation products and the change in molecular weight distribution were measured. The unoxidized polypropylene had no ultraviolet absorption at 253.7 nm, whereas the oxidized polypropylene showed distinct absorption over a wide range of molecular weights. It was found that oxygen was incorporated into the polymer chain as hydroperoxide, acid, carbonyl, and hydroxy groups. Much of the absorbed oxygen was found to be involved in smaller fraction of low molecular weight products. Although the average molecular weight of the oxidized polypropylene decreased significantly, the formation of low-boiling products was quite small.