Nonvolatile photorefractive holographic recording in Sc:Ce:Cu:LiNbO3

In this paper experimental studies of nonvolatile photorefractive holographic recording in Ce:Cu:LiNbO₃ crystals doped with Sc(0,1,2,3 mol%) were carried out. The Sc:Ce:Cu:LiNbO₃ crystals were grown by the Czochralski method and oxidized in Nb₂O₅ powders. The nonvolatile holographic recording in Sc:Ce:Cu:LiNbO₃ crystals was realized by the two-photon fixed method. We found that the recording time of Sc:Ce:Cu:LiNbO₃ crystal became shorter with the increase of Sc doping concentration, especially doping with Sc(3 mol%), which exceeds the so-called threshold, and there was little loss of nonvolatile diffraction efficiencies between Sc(3 mol%):Ce:Cu:LiNbO₃ and Ce:Cu:LiNbO₃ crystals.     

The Synthesis of Glycoglycerolipids

A convenient synthetic route was developed for the synthesis of the novel glycolipids: 1,2-di-O-acyl-3-O-(2‘-acylamide-2‘-denxy-ct-D-glucopyranosyl)-sn-glycerols. 10 new compounds of glycolipids with different acyl groups were obtained.     

凸度量空间中单值和集值映象的公共不动点定理

§ 1.　Introduction　　Anecessaryandsufficientconditionandasufficientconditiontoensurethataset valuedmappingandasingle valuedmappinginacompletemetricspaceandacompleteconvexmetricspacehavingacommonfixedpointarerespectivelygivenin [1 ] .Meanwhilethemainresultsin[2 ]— [5]areimprovedandextendedin [1 ] .Inthispaper ,theexistenceatcommonfixedpointsoftwoset valuedmappingandasing valuedmappingwerestudied ,andthecorrespond ingresultsin [1 ]— [5]wereextendedandimproved .Let(X ,d)beanon emptymetricspa…     

风冷热泵冷热水机组动态过程仿真

本文给出了风冷热泵冷热水机组动态过程模型。系统的高、低压段被分成制冷剂侧、管壁、以及水或空气侧三个控制容积。针对每个控制容积建立了质量和能量平衡的微分方程。由于压缩机、热力膨胀阀阀体、以及四通换向阀具有较小的热惯性,因而采用稳态模型描述压缩过程、膨胀过程、以及内泄露过程。膨胀阀感温包中的制冷剂温度对于蒸发器出口温度的延迟用一阶惯性环节来描述。通过“预测-校正”和“自适应步长”方法实现系统仿真。仿真结果与测试数据吻合良好。     

高考预效度的混合估计

用传统的预测效度估计法估计高考预测效度，其估计值往往偏低。为此，本文应用回归分析中混合估计理论提出了高考预测效度的混合估计。这种估计是预测效度的无偏估计，并解决了预测效度估计值偏低的问题。     

Interfacial effects on stress distribution in model composites

Raman mechanical spectroscopy was used to examine interfacial effects on the stress distribution in model polydiacetylene fiber/epoxy composites. Epoxy release agents were coated on fiber surfaces to modify the interfacial adhesion properties. The modified fiber surfaces were then characterized by scanning electron microscopy and x-ray photoelectron spectroscopy as well as optical microscopy. No difference in the maximum stress value or stress distribution was observed for the two types of fibers, coated or uncoated, used in composites. This suggests that adhesion properties at the composite interface do not affect tensile stress transfer efficiency nor, therefore, the composite tensile modulus along the fiber axis direction in uniaxial composites. Experimental data were also compared with theoretical calculations assuming perfect bonding between fiber and matrix, and idealized frictional force transfer mechanism at the fiber–matrix interface.     

CLIFFORD MARTINGALES Φ-EQUIVALENCE BETWEEN S（f） AND f^＊

ＣＬＩＦＦＯＲＤＭＡＲＴＩＮＧＡＬＥＳΦ－ＥＱＵＩＶＡＬＥＮＣＥＢＥＴＷＥＥＮＳ（ｆ）ＡＮＤｆ￥ＬＯＮＧＲＵＬＩＮ；ＱＩＡＮＴＡＯ（ＩｎｓｔｉｔｕｔｅｏｆＭａｔｈｅｍａｔｉｃｓ，ＡｃａｄｅｍｉａＳｉｎｉｃａ，Ｂｅｉｊｉｎｇ１０００８０，Ｃｈｉｎａ．）...     

浅析欧洲绿党政治

上个世纪70年代以来，绿党在欧洲政坛崛起，这是欧洲社会政治变化的一个新现象。绿党力量的上升乃至绿党政治的出现在某种程度上改变了西欧国家现行的政党格局。研究绿党对于我们了解欧洲政治变化以及绿色思潮与生态政治的影响具有重要意义。     

有效点、弱有效点和真有效点的锥刻画

利用集合在某点的相依切锥、法向锥和可行方向锥等研究向量优化问题的有效点、 弱有效点和真有效点的特征,对局部有效点、局部弱有效点和局部真有效点与集合的各 锥之间的关系作了刻画.     

Micromagnetic analysis of transition noise for high-density perpendicular recording

In this paper, specific issues related to high-density perpendicular magnetic recording processes, such as transition noise properties and cross-track correlation lengths, were investigated with the help of micromagnetic analysis. The effects of media parameters were taken into consideration, including intergranular exchange coupling, and exchange distribution, irregular grain shapes, magnetization saturation distribution, and anisotropy distribution. The micromagnetic simulation results showed that the effect of anisotropy distribution on transition noise is more significant than magnetization saturation distribution, and it is crucial to reduce this effect to achieve a high signal-to-noise ratio. Additionally, a new method to further estimate the partial erasure threshold was proposed to approximate the partial erasure effects, and the relation between the microtrack jitter and total track jitter was investigated.