A linear-time algorithm for finding optimal vehicle refueling policies

We explore a fixed-route vehicle refueling problem as a special case of the inventory-capacitated lot-sizing problem, and present a linear-time greedy algorithm for finding optimal refueling policies.     

酸根离子掺杂对多孔阳极氧化铝光致发光特性的影响

采用电化学二次阳极氧化法分别在纯硫酸、纯草酸及硫酸-草酸混合电解液中制备了3个系列的多孔阳极氧化铝(AAO)样品, 考察了它们在250 nm光激发下的光致发光(PL)特性. 研究结果表明, 各系列AAO样品在350～450 nm波段范围内的PL谱形均完全相似, 具有相同的发光中心, 即氧空位缺陷态; 掺杂进入AAO样品的SO₄^2-和C₂O₄^2-分解形成的发光中心对应的光发射分别在288和328 nm附近; 对于硫酸-草酸混合电解液中生长的AAO样品, 其在328 nm附近的发光峰随着硫酸-草酸体积比的增大呈先增大后减少的变化, 而288 nm附近的发光峰却由基本消失到逐渐显现. 初步分析了该现象的成因.     

STN型液晶显示用聚酰亚胺表面取向材料的性能

倾斜角;STN型液晶显示用聚酰亚胺表面取向材料的性能     

Isomerization of endo-tetrahydrodicyclopentadiene over clay-supported chloroaluminate ionic liquid catalysts

Various halide salts with different alkyl lengths were allowed to intercalate into the layer structure of sodium montmorillonite clay through an ion exchange reaction. Intercalation of 1-hexadecyl-3-methylimidazolium chloride, hexadecyltrimethylammonium bromide, dihexadecyldimethylammonium bromide, and tributylhexadecylphosphonium bromide could expand the spacing of the silicate layers from 12 to 37–41 Å (measured by X-ray diffraction). The modified clays were pretreated with the pyridine hydrochloride/AlCl₃ mixture and used for suitably supporting a chloroaluminate ionic liquid catalyst for the isomerization of endo-tetrahydrodicyclopentadiene into the corresponding exo-isomer. Nearly quantitative conversion to the desired product and nearly quantitative selectivity were observed for the newly developed clay-supported ionic liquid catalysts, which were proven to be recyclable.     

Structure and properties of (TiVCrZrY)N coatings prepared by energetic bombardment sputtering with different nitrogen flow ratios

(TiVCrZrY)N coatings were deposited onto Si substrate by the radio-frequency (RF) magnetron sputtering of a TiVCrZrY alloy target in an N₂/Ar atmosphere. The crystal, microstructural, mechanical, and electrical properties at different N₂-to-total (N₂+Ar) flow-rate ratio (R _N) values were investigated. The coating produced in pure Ar had an equiaxed structure with a hexagonal-close-packed phase. With increased R _N, the crystallinity and grain size markedly decreased. The microstructure of (TiVCrZrY)N coatings transformed from V-shaped columnar with a rough-domed surface into fine fibrous with a smooth surface. The amorphous transition layer above the substrate was also significantly thickened. The hardness of (TiVCrZrY)N decreased from 20.9 GPa to 18.9 GPa, and the electrical resistivity increased from 398.2 μΩ?cm to 21870 μΩ?cm.     

STN型液晶显示用聚酰亚胺表面取向材料的性能

与传统的扭曲向列 (TN)型液晶显示 (L CD)相比 ,超扭曲向列 (STN)型 L CD的信息容量和清晰度都有了很大的提高 ,已成为 L CD产品的重要组成部分 .为防止反倾斜 (reverse tilt)现象产生 ,液晶分子相对于取向膜表面必须具有一定的预倾角 .一般来说 ,TN型要求预倾角为 1～ 2°,STN型为 3～ 2 0°.稳定的大预倾角控制是 STN制造的关键技术之一 ,它直接影响到显示器件的对比度、阈值电压、响应时间、视角大小等特性 [1～ 4 ] .通过在聚酰亚胺分子长链中引入强极性基团或长烷基侧链可以获得大预倾角 [5～ 8] .本文合成了含有三氟甲基基团…     

乙烷类三环体系液晶的合成及其相变规律的研究

以反式-4-烷基环己烷甲酸为原料,合成了两个系列共14种乙烷类三环体系液晶。利用NMR、IR、DSC等确定了化合物的结构及相变温度,讨论了化合物的结构对相变温度的影响。     

The effect of oxalic and sulfuric ions on the photoluminescence of anodic aluminum oxide formed in a mixture of sulfuric and oxalic acid

Anodic aluminum oxide (AAO) films with highly ordered pore arrays were prepared in sulfuric, oxalic acids and their mixture solutions, respectively. The photoluminescence (PL) measurements show that AAO films formed in the mixture electrolytes have PL bands in the wavelength range of 300–450 nm, which mainly arise from the oxalic impurities incorporated into AAO films. However, the sulfuric ions have a strong effect on the PL bands. With the increase of the concentration of sulfuric ions in the mixture electrolyte, the blueshift of the PL bands occurs from 410 to 345 nm. The reasons of the results are being discussed.