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1.
讨论了用粒度的概念描述问题解搜索的基本理论,分析了EIS数据源和信息组织的特点并提出搜索的一般过程.以SXWG-EIS中外部信息模块为例,具体探讨了EIS中问题解搜索的过程和形式化描述.  相似文献   

2.
提出了一种背压控制EGR系统的设计方法.该系统由排气再循环阀和背压转换器组成,具有闭环反馈控制特性,保证汽油机在低负荷和全负荷时不进行EGR,在中高负荷区域则EGR流量随负荷增大而增大.给出了EGR流量的计算公式,讨论了该系统的结构参数对EGR流量的影响.  相似文献   

3.
图象压缩技术的分析与评价   总被引:1,自引:0,他引:1  
视频图象压缩是多媒体系统中的关键技术,其原理是通过消除视频信号中的冗余信息来减少信息量。文中首先分析了图象压缩的基本技术,其中包括空间冗余信息的压缩和时间冗余信息的压缩,并对这些压缩方法的理论依据和实用效果加以探讨。以此为基础,还重点分析了通过集成基本压缩技术而建立的以混合编码系统,特别针对现有的图象压缩国际标准如JPEG,MPEG和H.261等作了较为深入的探讨,对其系统结构,适用范围及有效性进行了比较和分析。  相似文献   

4.
提出了一种基于PSPICE4.02通用电路模拟程序与优化技术相结合提取GaAsMESFET模型参数的方法,根据实例的GaAsMESFET小信号S参数与大信号S参数,利用约束优化技术提取模型等电路元件参数,并利用该电路模型参数设计制作1了3.7GHz-4.2GHz和5.2GHz=-5.8GHz GaAsMESFET放大器,给出了设计和测试结果并验证了该方法的正确性。  相似文献   

5.
脑电信号的现代谱分析技术   总被引:1,自引:0,他引:1  
脑电信号是非平稳随机信号,它的频域特性的正确表达及精度,相位信息的提取,瞬态波形分析是当前EEG信号处理研究中的3个热点问题,本针对以上问题讨论了谱参量分析,双谱分析以及时间-频率域分析的原理,方法,并给出一些EEG信号处理的研究结果。  相似文献   

6.
本文概要介绍和分析了关于MPEG的音频标准,解释了关于MPEGI、MPEG2以及Layer1.2.3等方面读者关心和可能提出的一些问题;指出了选用标准应注意的问题;讨论了音质评价和联合立体声编码。  相似文献   

7.
图G=(V,E)的一个同构因子分解是边集E的一个划分:{E1,E2,…,Et},使得生成子图(V, E1),…,(V,Et)都彼此同构。若 H≌(V,E1),记为 H[G或 t]G.若对每个t≥2.当   时.均有:tG,则称G为有理图.文章证明了超立方图(hypercube)和超立方有向图都是有理图.  相似文献   

8.
用热台偏光显微镜和电子显微镜研究了PEG共聚物粘合体系在不同温度下的形态结构变化.比较网络结构表明,形态结构与PEG相对分子质量有关,随PEG相对分子质量增大,结晶倾向性增加.  相似文献   

9.
动作电位建立的一种新方法及其对ECG信号仿真影响的研究   总被引:2,自引:2,他引:0  
动作电位对正向心电的仿真研究至关重要,提出了一种动作电位的建立方法和各种心肌单元动作电位的确定途径,并给出了由此仿真的ECG信号,并结合临床ECG对结果进行了分析.  相似文献   

10.
合成了Eu(TTA)4Rh6G三元配合物(TTA:2-噻吩甲酰三氟丙酮;Rh6G:Rhodamine6G).对该配合物作了元素分析,DTA-TG分析和电导分析,测定了它的IR和UV吸收光谱,确定其化学组成为Eu:TTA:Rh6G=1:4:1,为离子缔合型.它的不同有机溶剂的溶液,在365nmUV灯照射下均能发出较强的荧光.其甲醇溶液和固态荧光光谱的最大发射峰分别为560.5nm和627.5nm.  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
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.  相似文献   

14.
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。  相似文献   

15.
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.  相似文献   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

17.
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.  相似文献   

18.
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.  相似文献   

19.
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-  相似文献   

20.
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-  相似文献   

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