激光在水中产生超声波的实验研究

用ＹＡＧ脉冲激光在自来水中产生超声波，用丹麦制造的水听器接收水中声波，在示波器上显示其波形并分析了产生声波的机理及特征，结果表明，当光源的脉冲宽度为８ｎｓ时，在混响声场中接收到声脉宽约为２ｍｓ；而在自由场中为１￣２μｓ，所以，在理想的情况下，声脉冲宽度应和光脉冲宽度同数量级。     

便于时钟提取的光时分复用信号产生装置

一种新型的由２×２光纤耦合器进行级联实现的８×２．５Ｇｂ／ｓ光时分复用信号产生装置,信号源采用增益开关量子阱ＤＦＢ激光器,产生脉冲宽度为４４ｐｓ,周期为４００ｐｓ的光脉冲信号．实验结果表明,采用这种方案制作的时分复用信号产生装置,可以产生便于非线性光环路镜进行时钟提取的８×２５Ｇｂ／ｓ时分复用信号,同时又可产生等幅的８×２．５Ｇｂ／ｓ时分复用信号．     

燕尾槽衬底内条形锁相列阵激光器亚纳秒光脉冲的产生及测量

报导了锁相列阵激光器产生的亚纳秒光脉冲，测得光脉冲宽度的典型值为２００ｐｓ，光脉冲的峰值功率可达３８０ｍＷ．     

脉冲光声量热法研究氧合血红蛋白的光解反应

时间分辨脉冲光声量热法是利用脉冲激光激发化学物质的光解反应,反应中产生的热能将激发声波,声波的振幅和相位即反映光解反应的中间过程.因此时间分辨光声量热技术是研究光致解离动力学信息的十分有效的方法.利用时间分辨光声量热法测量了激光诱导人、牛,猪、马和兔的氧合血红蛋白光解反应的焓变和结构体积变化.实验中采用波长532 nm、脉冲宽度8 ns的脉冲激光作为激发光源,光声信号由共振频率为1.5 MHz的PZT压电换能器接收,所以实验系统的响应时间范围在102 ns量级.已知在氧合血红蛋白的光解反应中可以检测到4个过程具有4种不同的反应时间,其中三级结构重组在137～470 ns左右.考虑实验系统的时间窗口,所测结果应与血红蛋白的三级结构变化相对应.测量结果显示:不同种类的哺乳动物氧合血红蛋白光解反应中,对应三级结构变化的焓变和结构体积变化各不相同.最后对这一结论进行了讨论.     

声频谱测井仪器的研制和野外实验

研制成功的声频谱测井仪器在井下发射和接收三种频率的声波信号,其中发射和接收20kHz声波信号的声系有一个发射和四个接收探头,源距为2.1~2.568m,间距为0.156m;发射和接收40kHz声波信号的声系由一个发射和两个接收探头组成,源距1.0~1.5m,间距0.5m;发射和接收10kHz声波信号的声系由一个发射和两个接收探头组成,源距为2.168~2.668m,间距0.5m.用三种不同的频率的声波进行测量记录目的是获得井壁径向深度不同处介质的声学信息,而且不同频率的声波信号在岩石中传播过程中频谱变化也是井壁岩层的可用声学信息.在井下的信息采集、数据传输、地面记录和监控全部由计算机控制.该仪器已经在大庆油田的三口井中成功的进行了野外实验.     

平面脉冲声波在多孔介质中传播的频移

利用传递函数,得到了平面脉冲声波在传播过程中任意位置处频谱的计算方法,用这种方法可以评价脉冲声波的主频偏移程度。给出了多孔介质中脉冲快纵波主频偏移的数值计算实例。计算结果表明,在一个有限的频带内,介质的声衰减与频率近似成线性关系,脉冲声波的主频偏移与介质的衰减、场点距声源的距离呈正比。该结果有利于利用脉冲声波的主频偏移来评价介质的声衰减     

基于多条耦合器声表面波器件的小波重构

提出了一种基于多条耦合器声表面波器件实现小波重构的新方案．利用基于多条耦合器声表面波器件的传递函数等于输入与输出加权换能器传递函数之积的关系，对输入、输出叉指换能器分别进行小波和重构小波加权，在单块器件上实现了小波重构功能，避免了二次插入损耗的产生．利用多条耦合器和双声路对称结构，将沿晶体表面传播的体声波进行了分离和消除，抑制了三次渡越信号，降低了接收损耗，使器件的响应特性得到了改善．实验结果表明，用新方案实现的小波重构器件比用早期方案实现的小波重构器件在插入损耗、体声波抑制、通带波纹和接收损耗方面均有明显的改善．     

平面脉冲声波在多孔介质中传播的频移

利用传递函数,得到了平面脉冲声波在传播过程中任意位置处频谱的计算方法,用这种方法可以评价脉冲声波的主频偏移程度,给出了多孔介质中脉冲快纵波主频偏移的数值计算实例,计算结果表明,在一个有限的频带内,介质的声衰减与频率近似成线性关系,脉冲声波的主频偏移与介质的衰减,场点距声源的距离呈正比。该结果有利于利用脉冲声波的主频偏移来评价介质的声衰减。     

等离子体焦点中的毫微秒脉冲沿面放电

等离子体焦点装置的性能与在装置中绝缘子表面上发生的初始击穿有关。本工作用毫微秒矩形脉冲发生器结合普通照相的方法研究了焦点装置中套管型绝缘子的沿面放电 发展过程，得到了时间分辩率达（５—１０）×１０－９ｓ的放电发展过程相片。放电沿绝缘子表面发展，其平均发展速度随所加脉冲幅值、宽度、极性以及放电室内的气压而变。当气压在５—２００Ｔｏｒｒ，脉冲幅值在６—１５ＫＶ，脉冲宽度在５—８０ｎｓ的范围内，放电发展速度在１０７—２×１０９ｃｍ／ｓ之间。试验指出，放电的发光通道连通两极后，放电通道并 不立即转变为良好的等离子体低阻通道。     

量子阱中的双极化子

在同时考虑电子与ＬＯ声子及ＩＯ声子相互作用的情况下,用ＬＬＰ正则变换的方法研究了半导体量子阱中双极化子的性质．给出了由于电子－ＬＯ声子及电子－ＳＯ声子相互作用而产生的诱生势,并且以ＧａＡｓ／Ａｌ０．３Ｇａ０．７Ａｓ为例进行了数值计算．通过计算可得出如下结论：（１）双极化子的诱生势可以分为两部分,其中一部分仅与一个电子的坐标ｚ１（ｚ２）有关,另一部分则不仅与两个电子的坐标ｚ１和ｚ２都有关,还与两个电子间的相对距离ρ有关;（２）诱生势ＶＩＬ（ρ）和ＶＩ,σ（ρ）的绝对值随着双极化子中两个电子间相对距离ρ的增加而减小;（３）由于电子与ＩＯ声子相互作用而产生的诱生势ＶＩ,σ（ρ）的绝对值随量子阱宽度Ｎ的增加而减小．本文方法适用于弱耦合和中耦合两种情况     

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.     

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.     

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.     

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.     

A computer generator for randomly layered structures

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

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-