基于相关光谱和差分检测的气体传感系统

基于相关光谱和差分检测技术提出了一种新型的光纤气体传感系统,实现了对微量气体的高灵敏度、高准确度、实时在线检测.首先对该系统进行了详尽的理论分析,然后在合理选择实验器件的基础上搭建了一个光纤气体传感系统,测量乙炔气体的体积分数.该系统不仅消除了光强波动及待测气体中杂质气体的干扰,而且也避免了周围环境中噪声和杂散光的影响.实验结果表明,系统的分辨力可达0.5‰,测量灵敏度为6.62μV,最大绝对误差为0.15‰,相对误差为7.5%,稳定性为2.27%,重复性误差为0.817%.     

基于空芯光子晶体光纤的反射式气体传感器

以光子晶体光纤(PCF)为研究对象,以提高气体测量灵敏度为研究目标,提出一种反射式的光纤气体传感技术.首先,利用宽谱光源谐波检测技术,并结合实际应用需求,设计了基于空芯PCF的反射式气体传感系统,并详细分析了系统的工作原理.然后,针对空芯PCF与单模光纤耦合困难、气体填充时间长的问题,设计了集密封、固定及连接于一体的机械耦合装置作为测量气室.最后,以乙炔气体为例,测试了该系统的传感特性,体积分数分辨力可达0.02%,最大相对误差为1.39%.该技术将进一步推动PCF在气体传感中的应用,并为其在实际气体浓度测量中的应用提供了理论和实验基础.     

微弱气体光声光谱监测光声信号影响因素分析

气体光声光谱检测技术灵敏度高,不消耗被测气体,能很好地应用于变压器油中溶解微弱气体的在线监测。检测中,微音器输出的光声信号是进行气体浓度分析的唯一特征量。基于光声光谱技术的基本原理,构建了一种便携式、可调谐的光声光谱装置。在分析气体光声信号激发机理的基础上,结合实验深入探讨了影响气体光声信号的多种因素,获得气体光声信号与压力、温度、激光功率、气体浓度、背景气体、斩波频率及谐振频率漂移之间的关系曲线,理论及实验结果为进一步完善油中气体光声光谱在线监测系统提供了技术参照和支撑。     

高灵敏度光纤气体传感器的研究

研究了差分吸收式光谱吸收型光纤气体传感器．基于NO2的光谱吸收特性,设计了一种检测NO2浓度的光纤传感系统,以LED作为光源,采用双波长差分检测技术,有效消除了由光源、光纤和传感头的不稳定所引起的检测误差,提高了检测灵敏度,大大增加了该传感器的适用性．     

差分吸收光谱技术在大气监测领域中的应用

随着人类经济的高速发展,环境污染和生态破坏日益严重,突发性环境污染事件也时有发生。如何防治污染、保护环境,成为当代科学的一个课题。痕量气体光谱分析技术检测大气污染具有检测范围广、速度快、成本低,且便于进行长期的动态检测等优势。差分光学吸收光谱技术(DOAS)是探测大气中痕量气体成分的现代光谱遥测技术。由于其高准确性和高分辨率、可同时对多种气体进行测量等优点被广泛用于城市空气质量、污染源排放(如:高速公路、企业排放)、对流层和平流层的大气痕量气体成分及自由基的测量。它可以同时测量大气中多种气体分子,如CO2、SO2、NOx等。本文介绍了主要介绍差分吸收光谱技术的原理、测量精度影响因素及其在大气监测领域中的应用。     

基于差分吸收光谱法的烷烃气体检测系统的研制

利用差分吸收光谱（DOAS）技术研制开发了一套烷烃类气体检测实验系统,在该实验系统上测量了CH4的吸收光谱以及吸收截面,并利用这些参数开展了CH4气体浓度反演算法的研究.实验结果表明：在常温常压下,CH4的检测结果与标准浓度之间的线性拟合系数R2为0.9998,误差小于3%,CH4的最低检测限为0.01%.这些工作为烷烃光谱录井仪的研发奠定了基础.     

烟雾箱内甲烷气体的腔增强吸收光谱

用DFB半导体激光器作光源的腔增强吸收光谱(CEAS)技术测量了烟雾箱中甲烷气体在近红外波段的光谱吸收,获得了烟雾箱内甲烷气体在1 315 nm附近的吸收光谱;将测得的光谱数据与Hitran 2004数据库给出的光谱参数做了比较,发现了几条尚未被Hitran 2004数据库收入的甲烷分子的新谱线;同时对CEAS技术定量测量烟雾箱内甲烷气体的能力和稳定性做了研究.结果表明,CEAS技术完全可以用来测量烟雾箱内甲烷气体的吸收光谱,可以作为烟雾箱检测方法的一种补充.     

基于TDLAS的甲烷传感器高灵敏信号处理方法研究

基于可调谐半导体激光吸收光谱,提出了一种新的数字信号处理方法用于提高吸收光谱测量的灵敏度。将该方法应用于瓦斯气体探测实验,研究结果表明：采用卡尔曼滤波可以使波长调制光谱的信噪比提高一个数量级,由于该方法不需要增加系统设备的成本,故比其他噪声抑制技术有更实用价值。     

LIBS技术在线检测重金属污染物的应用研究

指出了激光击穿光谱(LIBS)是一种新型的元素分析技术,具有灵敏度高、快速、可多元素同时测量并可在线检测等优点,非常适合针对环境中重金属污染物的实时在线检测.利用自行搭建的一套激光击穿光谱实验装置,开展了对烟气、污水、土壤中重金属的LIBS探测的实验研究,实验结果表明:LIBS技术为解决环境中重金属污染物的实时在线检测提供了技术支持,为将该技术利用到环境保护领域奠定了基础.     

离轴积分腔输出光谱技术在变压器油中甲烷气体检测中的应用

研究变压器油中溶解的甲烷(CH_4)气体的高灵敏光学检测方法。基于离轴积分腔输出光谱技术,利用分布反馈半导体激光器实现了一种CH4的离轴积分腔输出光谱检测装置。该装置对CH_4的检测灵敏度达到4.1u L/L,为变压器油中CH_4的在线监测设计提供了参考。     

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.     

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.     

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-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the