基于羧基氧化石墨烯的调Q光纤激光器

由于羧基官能团在碳原子层内以及边缘处的大量分布,羧基氧化石墨烯(Carboxyl-functionalized graphene oxide,GO-COOH)具有比石墨烯及氧化石墨烯更强的水溶性和生物活性,而且羧基氧化石墨烯的制备方法更加灵活、简单,使其在可饱和吸收体领域表现出一定的应用优势.将二维材料GO-COOH与聚合物聚乙烯醇(PVA)混合制成饱和吸收体薄膜,在掺铒光纤激光器中实现了稳定的调Q运转.泵浦功率为11-45mW时,激光器可以在12.05-22.52kHz重复频率范围内进行调谐,调Q脉冲的脉冲宽度的可调谐范围为19.81-4.66μs.当泵浦功率为45mW时,得到最小调Q脉冲宽度为4.66μs,最大单脉冲能量为117.68nJ.实验结果表明,羧基氧化石墨烯是一种有着广泛应用前景的二维非线性光学材料.     

基于MoS_2可饱和吸收体的Nd:GYSGG激光器双波长调Q及锁模的研究

利用真空蒸镀法制备了MoS_2可饱和吸收体,研究了Nd∶GYSGG激光器在1 057.28nm和1 060.65nm的双波长调Q及锁模运转特性.在泵浦功率为4W时获得重复频率为51kHz,最小脉冲宽度为831ns的调Q激光脉冲,以及重复频率为83MHz,脉冲宽度约为260ps的调Q锁模激光脉冲.激光器调Q运转的最大输出功率为0.25W,相应的光光转换效率为6.25%,得到最大单脉冲能量为4.9μJ.测得锁模脉冲最大输出功率为0.167W,相应的光光转化效率为3.96%.     

倏逝场作用氧化石墨烯大能量耗散孤子锁模双包层光纤激光器

报道了倏逝场作用氧化石墨烯的可饱和吸收体用于锁模掺镱双包层光纤激光器,产生大能量151.54nJ耗散孤子.利用熔锥光纤倏逝场诱导沉积氧化石墨烯方法,所制备的可饱和吸收体不仅拥有耐高功率、光纤兼容等优点;而且,熔锥光纤引入光带通滤波,有益于耗散孤子在光纤激光腔中形成.同时结合光纤包层泵浦技术,高脉冲能量耗散孤子在锁模掺镱双包层光纤激光器中被获得,产生的耗散孤子单脉冲能量高达151.54nJ,重复频率271.4kHz,信噪比57dB.     

掺Yb^3＋双包层光纤激光器

研究了掺Yb^3 双包层光纤激光器,测量了掺Yb^3 双包层光纤的荧光光谱特性和激光光谱特性,实验表明,中心波长为1.078μm的激光输出,最大输出功率为233mW,斜率效率为79.6%,光－光转换效率为30.2%。     

基于Nd:YAG/V:YAG键合晶体的1338 nm微片激光器研究

基于Nd:YAG/V:YAG键合晶体,在连续和准连续LD端面泵浦条件下,研究了输出波长1 338 nm的被动调Q微片激光器的输出特性。在连续泵浦条件下,最大的输出功率为0.73 W,此时得到稳定的调Q脉冲输出,脉冲宽度为139 ns。在准连续泵浦下,获得了被动锁模调Q激光输出,输出的最大功率为1.01 W,对应的脉冲宽度为80 ns,其中的锁模系列单脉冲宽度约为70 ps。实验结果表明,Nd:YAG/V:YAG键合晶体有利于获得高功率紧凑的1 338 nm脉冲激光输出,同时准连续泵浦能有效地降低激光晶体的热效应从而获得更高功率的激光输出。     

LD泵浦的Nd:LuVO4被动调Q激光器

报道了一种LD泵浦的被动调QNd:LuVO4激光器,其中,Cr4 :YAG作为可饱和吸收体,KTP作为倍频晶体.在注入泵浦功率为7.4W时,得到的最大平均功率为0.88W,最高重复频率为27kHz,最窄脉宽为14ns的1.06μm基频激光输出.在泵浦功率为7W时,得到的脉冲绿光的平均功率为271mW,重复频率,脉宽,单脉冲能量和峰值功率分别为12.5kHz,28ns,21.7μJ和0.77kW.     

双包层光纤激光器

双包层光纤激光器是目前研制出的功率最大的光纤激光器 ,它的激光输出功率可达几百瓦 .本文介绍了双包层光纤激光器的工作原理、优点、应用及其发展前景 .     

掺Yb3+双包层光纤激光器的输出特性分析

基于激光器稳态速率方程理论,分析了掺Yb3 双包层光纤激光器的输出特性,讨论了谐振腔结构、泵浦方式以及在近阈值和强泵浦情况下,输出反射镜的反射率对输出功率的影响。通过数值计算分析可知,对于F-P腔结构的双包层光纤激光器,采用后向泵浦比采用前向泵浦获得的输出功率大,增益分布也较后者平坦;在近阈值情况下进行泵浦,输出耦合镜有一个最佳反射率,使输出功率达到最大。一般反射率应取在0.4~0.7之间,但在强泵浦情况下,输出反射镜的反射率越低越好。同时还发现,由于光纤对激光存在着再吸收,因此在一定的泵浦功率下,增益介质长度存在一个最佳长度值,使输出功率达到最大。一般光纤应在70~90 m之间。     

高功率掺镱双包层光纤激光器双端泵浦的最佳功率分配

通过数值模拟研究了双端泵浦的高功率掺镱双包层光纤激光器的输出特性。首次提出当其他参数一定时,合理地分配正、反向泵浦光功率能够使得输出光功率最大,并对泵浦光功率分配问题作了详细的讨论;为提高光纤激光器的输出功率提供了理论依据。     

掺镱(Yb3+)双包层光纤激光器实验研究

光纤激光器具有转换效率高、光束质量好、散热方便、结构紧凑等优点,是高功率激光器领域的研究热点。本文设计了温控、水冷系统使半导体激光二极管泵浦源稳定在工作波长。通过设计的包层泵浦功率剥除器,有效地剥离了未被掺镱(Yb3+)双包层光纤吸收的泵浦光。采用20 W的半导体二极管激光器作为泵浦源,5 m长掺镱(Yb3+)双包层光纤作为增益介质,光纤光栅作为腔镜,在泵浦功率为19 W时,获得10.42 W的激光输出,激光波长1 062 nm,光-光转换效率约54.8%。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to