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1.
稀疏效应捕食-被捕食系统的持久性和周期轨道   总被引:3,自引:1,他引:2  
考虑一类稀疏效应非自治Volterra捕食系统,证明了该系统在某些条件下是持久的,而且,若该系统是周期系统,在某些条件下,它们存在唯一的严格正周期轨道,且是全局渐近稳定的。  相似文献   

2.
讨论一类具有Beddington型功能性反应的捕食者——食饵非自治系统,证明在适当的条件下,系统是持续生存的;若系统是周期系统,则在适当的条件下,该系统存在唯一全局渐近稳定的正周期解。  相似文献   

3.
考虑食饵为比Logistic模型的捕食者—食非自治系统,证明了该系统在某些条件下是持久的。而且,若该系统是周期系统,在某些条件下,它们存在正周期解又是全局渐近稳定的。  相似文献   

4.
从求解核磁共振系统Schroedinger方程的一般解出发,得到核磁共振系统产生A-A相的cyclic条件和循环初态条件。cyclic条件要求系统的频率只能取离散的序列而初态可以是任意的;循环初态条件要求对系统的初态作一定的限定而系统的频率可以是任意的。在此基础上计算出系统在满足cyclic条件和循环初态条件时产生的A-A相,在cyclic条件下,系统产生的A-A相是依赖于初态和大于1的自然数的离散序列;在循环初态的条件下,系统产生的A-A相仅依赖于频率。证明了在绝热极限下,从这两类A-A相可以严格获得Berry几何相。  相似文献   

5.
非自治捕食—食饵扩散系统的渐近性质   总被引:4,自引:0,他引:4  
讨论了一个非自人有第Ⅱ类功能性反应九的两种群捕食-食饵系统,一个种群可以在两个斑块间扩散,另一种群限制在一个斑块上,证明了在适当条件下,系统是永久持续生存的;若系统是周期系统,则在适当条件下,该系统存在惟一的全局吸引的正周期解。  相似文献   

6.
一类捕食与被捕食系统的持续生存性与周期解   总被引:3,自引:0,他引:3  
讨论了一类一个捕食者种群和两个食饵种群构成的非自治生态系统.系统中食饵种群有各自的避难所,它们在避难所内外可以迁移.应用常微分方程定性和稳定性的方法,得到了在一定条件下系统是持续生存的;进一步,若系统是一个周期系统,则在合适的条件下,系统存在唯一的、全局渐近稳定的周期解  相似文献   

7.
浅谈高校办公自动化系统建设   总被引:4,自引:1,他引:4  
办公自动化系统建设是高校工作现代化建设的一项重要内容,是提高高校在高技术教育条件下整体工作能力的有效途径。对高校在高技术条件下如何搞好办公自动化系统建设提出了几点建议。  相似文献   

8.
本文针对一类舍有状态时滞的双积分器模型的时离散多智能体系统,在两种通信协议条件下,研究了它的可控性问题。我们应用化时滞系统为其等价的无时滞的增广系统的方法,获得了由跟随者构成的系统在多个领航者的控制下,系统可控的一些充分条件。在这些条件下,系统可以完成预期的编队控制或速度控制。  相似文献   

9.
讨论了一类一个捕食者种群和两个食饵种群构成的非自治生态系统,系统中食饵种群有各自的避难所,它们在避难所内外可以迁移,应用常微分方程定性和稳定的方法,得到了在一定条件下所得持续生存的;进一步,若系统是一个周期系统,则在合适的条件下,系统存在唯一的,全局渐近稳定的周期解。  相似文献   

10.
讨论了周期Lotka—Vo1terra反应扩散竞争系统在齐次Dirichlet边值条件下正周期解的存在性和全局渐近性态,在关于系数的一定条件下证明了该系统是持续生存的.  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.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
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   

15.
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   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

19.
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   

20.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

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