Distributed-Controlled Multiagent Mobile Platform with Digital Actuation Concept for Space Applications

This paper describes an architecture for a multiagent robotic system that consists of a number of identical units. The homogeneous units are mechanically connected to construct a mobile platform named a “multiagent transportation (MAT) system.” Every unit has its local controller that communicates only with its adjacent units. This basic configuration of supervisorless structure affirmatively confines the dependence of each unit to a local area, and therefore any unit can be removed from or added into any part of a MAT system regardless of the timing and without disturbing the performance of the whole system. This flexibility of configuration significantly contributes to easy maintenance of units, such as battery charging or hot-replacing for faulty units. Utilizing this flexibility, MAT systems are able to adapt to a variety of tasks including transportation application and to target objects of various shapes and range of mass. These characteristics of MAT systems are the strong advantages for mobile robots, especially for ones activated in distant places, e.g., robotic planetary explorers. A proposed example unit of a MAT system shown in this paper employs a parallel link manipulator as its leg, and the digital-actuation (D-actuation) concept is applied for the local unit controller to actuate the leg. Together with the basic design of the example units, the controlling framework is described with simulation results to show the feasibility of the whole mobile system architecture.     

Damage of yeast cells induced by pulsed light irradiation

DNA damage, such as formation of single strand breaks and pyrimidine dimers was induced in yeast cells after irradiation by pulsed light, which were essentially the same as observed with continuous ultraviolet (UV) light. The UV-induced DNA damage is slightly higher than seen with pulsed light. However, increased concentration of eluted protein and structural change in the irradiated yeast cells were observed only in the case of pulsed light. A difference in the inactivation effect between pulsed light and UV light was found and this suggested cell membrane damage induced by pulsed light irradiation. It is proposed that pulsed light can be used as an effective sterilizing method for the yeast Saccharomyces cerevisiae.     

高阶流形方法及其应用

流形方法是一种可进行连续与非连续变形问题分析的灵活而有效的数值计算方法。本文详细地推导了二阶流形方法的具体计算列式,分别开发了一阶流形方法与二阶流形方法的计算程序．通过实例计算表明：提高覆盖函数的阶次可有效地提高流形方法的计算精度。     

Fabrication of micro-patterned TiO2 thin films incorporating Ag nanoparticles

A photosensitive TiO₂ thin film embedded with Ag nanoparticles has been prepared from a Ti(OBu)₄–acetylacetone solution, containing dispersed Ag nanoparticles, by the sol–gel method. UV–visible absorption spectra showed that the thin film obtained has two absorption bands, characteristic of the acetylacetone chelate rings and plasmon resonance from Ag nanoparticles. After the irradiation of UV light, the absorption band from the chelate rings almost disappeared, ascribed to structural changes associated with dissociation of the chelate rings. The thin film after the UV irradiation exhibited a broad absorption band in the IR spectrum, indicating that a Ti–O–Ti network was formed in the thin film. HRTEM and EDX spectra revealed that Ag nanoparticles were present and dispersed in the TiO₂ thin film. Micro-patterns of 50 μm dots have been fabricated by UV irradiation through a corresponding photomask, followed by leaching.     

HDPE膜预辐照接枝VBTAC制备阴离子交换膜

在氮气保护下,利用预辐照接枝技术在高密度聚乙烯(HDPE)膜上接枝苯乙烯三甲基氯化铵(VBTAC)单体,以甲基丙烯酸二甲氨基乙酯(DMAEMA)单体作为接枝辅助单体来提高VBTAC的接枝率,制备出阴离子交换膜,解决了在HDPE上难以直接接枝聚合VBTAC的问题.本文研究了接枝条件及接枝液的组分对接枝的影响,并用X射线显微分析方法研究了VBTAC的接枝进程和接枝分布.     

Improvement of poly(vinyl alcohol)/poly(vinyl pyrrolidone) blended hydrogel by radiation crosslinking

1IntroductionHydrogelisapolymericmaterial(syntheticornaturaJ)whichswellswhenplacedincontactwithwaterbutisnotsolubleandhastheabililtytoretainwaterwithinitsstructare.InIecentyears,muchattentionhasbeenfocusedontheresearchanddevelopmentofthepolymerhydIogelsforbiomaterials,suchascontactlenses,wounddressing,enzymeimmunoassay,cathetersanddIugdeliverysystems[1~3].Adressingisoftencoveredonthewotmdtoaccelerateitshealing.TheIearetwokindsofdiessings:drytypeandwettype.Ithasbeenreportedthatheallngwithawe…     

Electrical properties of high purity tin dioxide doped with antimony

The electrical conductivity of high purity tin dioxide doped with antimony was studied at temperatures of 900 to 1200° C and partial pressures of oxygen between 10^–8 and 1 atm. For specimens having a dopant concentration over 1 × 10¹⁹Sb cm^–3, the electrical conductivity decreased slightly with temperature and independent of oxygen partial pressure. The electrical conductivity of specimens having a dopant concentration under 1 × 10^–8Sb cm^–3 increased with temperature and with decreasing partial pressure of oxygen. The significance of the dopant and the thermally created defects is discussed.     

New amphoteric surfactants derived from lysine. I. Preparation and properties of Nε-acyllysine derivatives-acyllysine derivatives

New amphoteric surfactants were prepared from N^ε-acyllysine which was obtained by the thermal dehydration of a higher fatty acid salt of lysine and was not soluble in water. N^α,N^α-dimethyl-N^ε-acyllysine was prepared by the catalytic reductive condensation of N^ε-acyllysine ester with formaldehyde in good yield. N^α,N^α,N^α-trimethyl-N^ε-acyllysine was obtained from the reaction of N^α,N^α-dimethyl-N^ε-acyllysine ester with methyl iodide. Confirmation of the structure of these derivatives was obtained by spectrometric and spectroscopic analyses. The solubility of N^ε-acyllysine was improved significantly by the introduction of N^α-methyl groups. Physicochemical and surface active properties of the derivatives were investigated in terms of isoelectric points, dissolution temperatures, surface tensions, critical micelle concentrations (cmc), foaming properties and wetting powers. N^α,N^α,N^α-trimethyl-N^ε-acyllysine had lower dissolution temperatures than N^α,N^α-dimethyl-N^ε-acyllysine. The latter showed lower surface tensions than the former at cmc. N^α,N^α-dimethyl-N^ε-lauroyllysine was best in wetting power and foaming property.     

Electrical conductivity of yttria-stabilized zirconia single crystals

The electrical conductivities of YSZ single crystals with various compositions covering FSZ and PSZ regions were measured by a complex impedance method and a four-probe a.c. method. The conductivities changed significantly as a function of composition. A simple conduction model for PSZ showed that the tetragonal phase is a good oxygen ionic conductor having an activation energy for motion of about 0.8 to 0.9 eV. It is promising for low temperature application of a solid state electrolyte.