属性权重未知情形下的q阶orthopair犹豫模糊TOPSIS法

在多属性决策问题中,q阶orthopair犹豫模糊集可以有效地处理不确定信息.基于Theil不等系数,提出一种新的q阶orthopair犹豫模糊距离测度,并研究该距离测度的性质.针对属性权重完全未知的q阶orthopair犹豫模糊多属性决策问题,构建离差最大化的属性权重模型.基于该权重确定模型和q阶orthopair犹...     

Achieving uniform field emission from carbon nanotube composite cold cathode with different carbon nanotube contents: Effects of conductance and plasma treatment

A carbon nanotube (CNT) composite cold cathode was studied for field emission display application. The CNT composite cold cathode was composed of CNTs and silicon dioxide binder. Field emission from CNT composite cold cathode with different CNT contents was studied. It was found that with increase in CNT contents, the threshold field decreased. The conductance of the composite cathode was measured and with increasing CNT content, there was a critical CNT content where the conductance increased several orders of magnitude. Plasma etching using SF₆ as the etchant was adopted to treat the cathode. Improvement in emission uniformity was achieved. It was also found that after post-treatment the threshold field of the cathode decreased. The morphology of the etched cathode was analyzed and the improvement of uniformity and lowering of the threshold field was attributed to the exposure of CNTs after etching.     

Synthesis of CeB6 thin films by physical vapor deposition and their field emission investigations

High quality CeB₆ thin films have been obtained through direct evaporation of raw micron-sized CeB₆ powders at a pressure of 70 Pa. The X-ray diffraction (XRD), Raman spectrum, scanning electron microscope (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and the field-emission equipment were used to characterize the morphology, structure, composition and FE properties of the samples. The XRD and Raman spectrum analysis results show the as-prepared product is cubic phase CeB₆. The TEM, SAED and HRTEM analysis reveal that the samples are mixtures of thin films (polycrystalline) and small crystals (single crystallines aligned preferentially in the [1 1 0] direction). Compared to oxide nanostructures, field-emission measurements show that the CeB₆ films have better FE performance with turn-on field and threshold field of 12.93 V/μm and 14.86 V/μm, respectively.     

Field emission properties of composite nano-Au/DLC films prepared by CVD technique

Nanocrystalline gold incorporated diamond-like carbon (nano-Au/DLC) films were deposited by capacitively coupled plasma (CCP) r.f. chemical vapour deposition (CVD) technique. Gold content in the DLC matrix was controlled by the amount of argon in the argon + methane mixture in the plasma. Field emission properties of these films were studied critically. Bonding environment (sp²/sp³ ratio) in these films was obtained from Raman measurements. Modification of the surface with the incorporation of gold nanocrystallites and associated modulation of sp²/sp³ ratio in the films culminated in improved field emission properties. Fowler-Nordheim model was used to ascertain the work function (?) which varied between 19 and 64 meV. The field factor (β) varied between 172 and 1050.     

实验室模拟控制轧制和调质处理对桥梁钢Q690q组织和性能的影响

研究了920℃精轧,830℃终轧以12℃/s冷至590℃,空冷的TMCP控制轧制工艺和TMCP+940℃淬火-630℃回火两工艺的桥梁钢Q690q(/%:0.05C、0.30Si、1.40Mn、1.10Cu、0.50Cr、0.80Ni、0.07V、0.55Mo,焊接冷裂纹敏感指数P_cm≤0.267)15mm板组织和力学性能。结果表明,TMCP工艺生产的桥梁钢Q690q组织主要由粒状贝氏体和少量铁素体组成,TMCP+调质处理后的组织为多边形铁素体和少量渗碳体,其屈服强度R_p0.2为845～870MPa,抗拉强度Rm895～900MPa,-20℃冲击功153～186J, -40℃为141～155 J。调质处理减小了钢材的M/A岛尺寸和位错密度,使Q690_q钢保持高强度的同时也具有较好的冲击韧性。     

Oxidation kinetics of Ni metallic films: Formation of NiO-based resistive switching structures

Resistive switching controlled by external voltage has been reported in many Metal/Resistive oxide/Metal (MRM) structures in which the resistive oxide was simple transition metal oxide thin films such as NiO or TiO₂ deposited by reactive sputtering. In this paper, we have explored the possibility to form NiO-based MRM structures from the partial oxidation of a blanket Ni metallic film using a Rapid Thermal Annealing route, the remaining Ni layer being used as bottom electrode. X-ray diffraction was used to apprehend the Ni oxidation kinetics while transmission electron microscopy enabled investigating local microstructure and film interfaces. These analyses have especially emphasized the predominant role of the as-deposited Ni metallic film microstructure (size and orientation of crystallites) on (i) oxidation kinetics, (ii) NiO film microstructural characteristics (crystallite size, texture and interface roughness) and (iii) subsequent electrical behavior. On this latter point, the as-grown NiO films were initially in the low resistance ON state without the electro-forming step usually required for sputtered films. Above the threshold voltage varying from 2 to 5 V depending on oxidation conditions, the Pt/NiO/Ni MRM structures irreversibly switched into the high resistance OFF state. This irreversibility is thought to originate in the microstructure of the NiO films that would cause the difficulty to re-form conductive paths.     

Evolution of soluble carbohydrates during the development of pea, faba bean and lupin seeds

Seeds of pea (Pisum sativum L. cv. Ergo), faba bean (Vicia faba ssp. minor Harz., cv. Tibo) and yellow pea lupin (Lupinus luteus L. cv. Juno) were sampled at different days after flowering (DAF) and their content of soluble carbohydrates was determined: Analysis of samples showed thatmyo-inositol, fructose, glucose, galactose and sucrose were found in high abundance early in development and their content decreased gradually during maturation. q112707/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-Galactosides, which includes the content of raffinose, stachyose and verbascose, started to appear later in seed development, at 37 DAF in peas, 40 DAF in faba beans and 45 DAF in lupins. Their accumulation increased considerably during seed growth, and the maximum content was obtained in mature seeds; 3.8% in peas, 4.5% in faba beans and 10.4% in lupins. Results obtained for these sugars during seed development were fitted to modelling curves in order to predict sugar content at different development stages.     

Enhanced magnetization and magnetoelectric coupling in hydrogen treated hexagonal YMnO3

The single phase hexagonal YMnO₃ has been synthesized via sol-gel route by adopting two different sintering conditions. In one case, sintering has been done at ∼700 °C in Ar/H₂ atmosphere and in other case it has been done at ∼1250 °C in air. Magnetic measurements of the samples, synthesized by sintering at relatively lower temperature in Ar/H₂ atmosphere, show the enhanced ferromagnetic behaviour at 10 K. M-H curve shows that the value of saturation magnetization (M_s) at 10 K is 8.04 emu/g for Ar/H₂ sintered sample while it is 2.93 emu/g for the air sintered sample. Moreover, a weak ferromagnetic signal at room temperature has been observed in YMnO₃ compound. Magnetization versus magnetic field (M-H) curves of hydrogen treated samples, measured at room temperature, show small kink in the linear variation near origin, possibly due to presence of weak ferromagnetic interactions in the samples at room temperature. However, the polarization-electric field (P-E) curve shows weak ferroelectric characteristics for the Ar/H₂ sintered samples. It is suggested that the enhanced ferromagnetism in Ar/H₂ sintered sample originates from the presence of oxygen vacancies in the Ar/H₂ sintered samples. Moreover, the magnetoelectric coupling coefficient at room temperature is improved to 106 mV/cm Oe for Ar/H₂ sintered sample as compared to 96 mV/cm Oe for air sintered sample at 40 kHz ac magnetic field frequency.