关于“不动点的单调原理”的条件的修正(英文)     

卢同善 《中国海洋大学学报(自然科学版)》1990,(3)

Taskovic,M R于1985年建立的“不动点的单调原理”,经作者证明是错误的。本文以另外的条件来代替“不动点的单调原理”中的所谓“AT—型条件”,建立了相应的不动点定理。该定理是某些重要结果的进一步推广。  相似文献   

随机集值映射的一个不动点定理     

卢同善 《中国海洋大学学报(自然科学版)》1987,(2)

随机不动点定理在随机泛函分析中起重要作用。最近,随机集值映射的不动点定理得到了广泛地研究。本文研究具有随机定义域的随机集值映射的一个新的不动点定理,这一定理推广了S.Reich等人的重要结果。  相似文献   

基于FLUS模型与动能定理的城镇用地增长边界划定     

黄康  戴文远  黄万里  欧惠 《地球信息科学学报》2020,22(3):557-567

城镇用地增长边界能够有效控制城市的无序蔓延,对城市健康持续发展具有重要意义。当前针对城镇用地增长边界划定的研究多采用较为成熟的元胞自动机(CA)模型对城市未来格局进行模拟,且研究多集中于单一的城镇用地增长边界划定,尚无对城镇用地增长的惯性边界进行定量划定,而划定惯性边界不仅能够为城市发展预留一定的用地空间,也能提高城市规划的实施效率。对此,本文以2000、2009和2015年福州中心城区土地利用数据为基础,采用FLUS模型进行土地利用模拟,并对模型精度进行了验证(2015年土地利用模拟总体精度达到0.9389,Kappa系数达0.9165),据此预测了2027年的土地利用格局,从中提取城镇用地采取形态学的膨胀与腐蚀法(MED)进行增长边界的划定。在此基础上,本文提出了一种借鉴力学动能定理划定城镇用地增长惯性边界的方法,以坡度和地类作为摩擦力参数,对福州中心城区城镇用地增长惯性边界进行了研究。结果表明,FLUS模型和MED能够有效地对土地利用进行模拟且能较好的对城镇用地增长边界进行拟合;借鉴动能定理的方法能够根据城市不同方向的扩展阻力和各个方向的扩展强度较好地划定其惯性边界,具有现实可操作性和实际参考价值。  相似文献   

Inferring trip purposes and uncovering travel patterns from taxi trajectory data   总被引：9，自引：0，他引：9  

Li Gong  Xi Liu  Lun Wu 《制图学和地理信息科学》2016,43(2):103-114

Global positioning system-enabled vehicles provide an efficient way to obtain large quantities of movement data for individuals. However, the raw data usually lack activity information, which is highly valuable for a range of applications and services. This study provides a novel and practical framework for inferring the trip purposes of taxi passengers such that the semantics of taxi trajectory data can be enriched. The probability of points of interest to be visited is modeled by Bayes’ rules, which take both spatial and temporal constraints into consideration. Combining this approach with Monte Carlo simulations, we conduct a study on Shanghai taxi trajectory data. Our results closely approximate the residents’ travel survey data in Shanghai. Furthermore, we reveal the spatiotemporal characteristics of nine daily activity types based on inference results, including their temporal regularities, spatial dynamics, and distributions of trip lengths and directions. In the era of big data, we encounter the dilemma of “trajectory data rich but activity information poor” when investigating human movements from various data sources. This study presents a promising step toward mining abundant activity information from individuals’ trajectories.  相似文献   

加筋路堤临界高度上限分析     

张晓咏  刘毓氚 《岩土力学》2006,27(Z2):225-228

依据加筋理论,假定加筋路堤边坡的破裂面为对数螺旋面,运用极限分析的上限原理推导加筋路堤临界高度的上限解。在不计加筋力时,该解与无筋路堤的临界高度一致。结合算例,得出加筋能提高路堤临界高度的结论。  相似文献   

Wellbore flow‐rate solution for a constant‐head test in two‐zone finite confined aquifers     

Chi‐Shan Tsai  Hund‐Der Yeh 《水文研究》2012,26(21):3216-3224

The solution describing the wellbore flow rate in a constant‐head test integrated with an optimization approach is commonly used to analyze observed wellbore flow‐rate data for estimating the hydrogeological parameters of low‐permeability aquifers. To our knowledge, the wellbore flow‐rate solution for the constant‐head test in a two‐zone finite‐extent confined aquifer has never been reported so far in the literature. This article is first to develop a mathematical model for describing the head distribution in the two‐zone aquifer. The Laplace domain solutions for the head distributions and wellbore flow rate in a two‐zone finite confined aquifer are derived using the Laplace transform, and their corresponding time domain solutions are then obtained using the Bromwich integral method and residue theorem. These new solutions are expressed in terms of an infinite series with Bessel functions and not straightforward to calculate numerically. A large‐time solution for the wellbore flow rate is therefore developed by employing the relationship of small Laplace variable versus large time variable and L'Hospital's rule. The result shows that the large‐time solution is identical to the steady‐state solution obtained after applying the Tauberian theorem into the Laplace domain solution. This large‐time solution can reduce to the Thiem equation in the case of no skin. Finally, the newly developed solution is used to investigate the effects of outer boundary distance and conductivity ratio on the wellbore flow rate. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Effect of oblateness on the non-linear stability of the triangular liberation points of the restricted three-body problem in the presence of resonances     

Navin Chandra  Ranjeet Kumar 《Astrophysics and Space Science》2004,291(1):1-19

The non-linear stability of the triangular libration points of the restricted three-body problem is studied under the presence of third and fourth order resonance's, when the more massive primary is an oblate spheroid. In this study Markeev's theorem are utilised with the help of KAM theorem. It is found that the stability of the triangular libration points are unstable in the third order resonance case and stable in the fourth order resonance case, for all the values of oblateness factor A₁. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Failure mechanisms of post-earthquake bedrock landslides in response to rainfall infiltration   总被引：1，自引：0，他引：1  

Yong Wu  Siming He  Yu Luo  Xinpo Li 《山地科学学报》2011,8(1):96-102

Among the triggering factors of post-earthquake bedrock landslides,rainfall plays an important role.However,with slope variation,the mechanism of its effects on the failure of rock landslides is not clear.Here,from the viewpoint of fracture mechanics,and based on post-earthquake conditions,the mechanisms of crack propagation,water infiltration and development of the sliding surface were investigated.Then,according to the upper boundary theorem,the effects of water infiltrated into fractures on the stability of rock slopes were analyzed quantitatively.Finally,an example is presented to verify the theory.The results show that the propagation and coalescence of cracks and the lubrication of incipient sliding surfaces are the main causes of the failure of post-earthquake rock landslides in response to rainfall.  相似文献   

On the successive elimination of perturbation harmonics     

Alessandro Morbidelli 《Celestial Mechanics and Dynamical Astronomy》1993,55(2):101-130

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积分第二中值定理“中值点”渐近性探讨     

胡洪萍 《地球科学与环境学报》1997,(Z1)

本文研究了积分第二中值定理“中值点”的渐近性，得出了一般性的结果。  相似文献