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岩土工程数值计算中的无网格方法及其全自动布点技术 总被引:14,自引:3,他引:11
自然单元法采用无网格的思想全域构造插值函数,它的求解精度高,计算时间少,可准确地施加边界条件,兼具有无网格法和有限单元法的优点和特点,是一种理想的用于岩土及地下工程分析计算的数值方法。文中简要地介绍了自然单元法的基本理论,并针对岩土及地下工程问题特点,给出了一种无网格离散点的全自动布置方法。 相似文献
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While community forestry has shown promise to reduce rural poverty, improve reforestation and potentially offset carbon emissions, many projects have failed, either partly or completely. In order to understand why community forestry succeeds or fails, we examined in detail the literature related to community forestry from three countries, Mexico, Nepal and the Philippines. We also drew on experiences in other countries in Asia, Latin America and Africa. We identified five main interconnected factors which the literature suggests are often critical to the success of community forestry. To integrate the many ways in which community forestry projects can improve the state of these factors, we use the concept of ‘bonding social capital’, i.e. communities’ ability to work together towards a common aim and ‘bridging social capital’, i.e. their ability to liaise with the outside world. To understand the interaction of the five success factors and the way in which improvements to bonding or bridging social capital may affect them, we developed a causal diagram which depicts the interrelationships between the success factors and the key points at which project inputs may be best applied. It is clear from our analysis that failing to appreciate both the complexity and interaction of the various influences may lead to project failure. 相似文献
195.
A. L. Tadross 《Astronomische Nachrichten》2023,344(10):e20230073
Most astrophysical parameters of the two stellar clusters Majaess 95 and Majaess 225 have been investigated here for the first time using the third data release of the Gaia space mission (Gaia-DR3). The membership probabilities of stars were assigned using the pyUPMASK algorithm. The parallaxes offset has been corrected using the zero-point correction code of Lindegren et al. (Lindegren et al. 2021, A&A, 649, A4). Using the clusters' members with membership probabilities >0.50, we calculated the distance to the clusters of 3311 and 3020 (±130) pc, respectively, which agree with the results from our isochrone fitting on the color-magnitude diagram. The ages are found to be 282 (±20) and 12.6 (±2) Ma. Also, the reddening, heliocentric distances, luminosity function, mass function, and total mass were estimated. On studying the dynamic state (relaxation time), we found that Majaess-95 is a relaxed cluster, while Majaess-225 is not relaxed yet. 相似文献
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提出一种基于网络Voronoi面域图的最大覆盖选址模型及相应的粒子群优化方法,并应用于城市响应时间敏感型公共服务设施的空间优化。本文考虑设施功能沿交通网络辐射以及需求非均匀分布情形,对设施在网络连续空间上进行布局优化,选址模型采用网络Voronoi面域图划分布局设施的功能辐射域,以启发空间优化最小化重叠覆盖。模型同时顾及了设施利用率的最大化,规定设施对给定距离以内的需求实行的完全服务覆盖和对给定距离以外的需求实行随距离衰减的部分服务覆盖。本研究提出基于遗传机制和广义Voronoi图改进的粒子群算法以提高其空间优化性能,通过对南京市消防站最大覆盖空间优化实验表明,该研究取得了较为理想的结果,可应用于城市化区域应急设施最大覆盖空间优化。 相似文献
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Seawater desalination is a rising technology intended to overcome water scarcity and is increasingly being used for the production of drinking water. A good quality pretreatment process is prominent to the successful operation of a Seawater Reverse Osmosis (SWRO) plant. The tasks of the intake and the pretreatment modules are to prevent fouling and to extend the lifetime of the reverse osmosis membranes. To practice the method of assessment design, 19 seawater plants with 11 different design strategies have been evaluated. The assessed strategies consist of: (i) Intake treatment, (ii) pretreatment aid (coagulation, flocculation, clarification), and (iii) pretreatment unit. Every possible combination of the design elements has been evaluated by a set of 15 attributes. The comparative evaluation has been conducted by Hasse diagram technique (HDT) using PyHasse software. The result of the HDT application includes 7 favorable incomparable design strategies. In order to solve the incomparability, the Condorcet–Kemeny–Young–Levenglick (C–K–Y–L) ranking procedure was additionally used and rendered the optimal design that is based on subsurface intake and membrane (ultrafiltration) pretreatment facilities. According to the results, both mathematical methods, i.e., the HDT in combination with the C–K–Y–L, procedure can be powerful and helpful tools to assist decisions concerning design strategies. 相似文献
200.
A study on the mixing proportion in groundwater samples by using Piper diagram and Phreeqc model 总被引:1,自引:0,他引:1
Karmegam U. Chidambaram S. Prasanna M.V. Sasidhar P. Manikandan S. Johnsonbabu G. Dheivanayaki V. Paramaguru P. Manivannan R. Srinivasamoorthy K. Anandhan P 《中国地球化学学报》2011,30(4):490-495
Piper (1944) diagram has been the basis for several important interpretations of the hydrogeochemical data. As seen in this diagram, most natural waters contain relatively few dissolved constituents, with cations (metals or bases) and anions (acid radicles) in chemical equilibrium with one another. Apart from the facies representation, the composition of the mixed sample can be identified in terms of the composition of the parental solution. To bring out this advantage of the Piper diagram, a study was conducted in the Kalpakkam region of Tamilnadu, South India. By taking the geology and water table into consideration, two sample locations were selected as parent solution and third one as the mixture sample. All three samples were analyzed for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chloride (Cl), sulphate (SO4) and phosphate (PO4) by Ion Chromatograph (Metrohm IC 861). HCO3 was determined by volumetric titration. The Piper diagram shows that parent solutions clustered towards Na-Mg-Ca-HCO3-Cl and Na-HCO3 facies, and the mixing sample belongs to Na-Mg-HCO3 facies. Phreeqc interac-tive (Ver 2.8) along with the original composition of the mixture sample was used to correlate the mixing proportion identified by the Piper diagram. 相似文献