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311.
Zhou Zhaode 《地理学报(英文版)》1994,(Z1)
I.Introducti0I1Hail1al1isthelargnsttropicalislal1dwitllabundal1t11aturalrcsourccssuitablef0rgrowtllgtrol,icalcropsand\\4t11ven'highp0tentia1pr0d,uctivity.Hotx'cY'cr,t11c1-ca1'cstillsomeproblemsf(l)Tl1ese1ectionoflandsuitableforfqrestisn0tstrictalldPreservativerateoftr0picalcr0psislow,(2)Mostoftropicalcr0psarecollccntratcdillthezoneofeastern"windgap"andnorthern"frigidplace"andtheirsecurityisnotstable,(3)Rubberareaaccountsforab0uttwo-thirdsoftl1etotalarea0ftropica1crops,henceproportiondis1ocat… 相似文献
312.
Christian Wichmann Matthiessen 《GeoJournal》2004,61(1):31-39
Copenhagen in Denmark and Malmö in Sweden were connected in 2000 by the 18- km fixed Öresund link. This meant that the time distance-barrier was reduced dramatically and that the land-sea bottleneck was eliminated. High-profile pre-bridge expectations of a new regional development regime towards a functionally integrated, bi-national region are assessed in this paper. The paper relates to the continuing discussion on development of border-regions and bi-national cities. Data on cross-Öresund flows of people and vehicles, together with data on migration and commuting, indicates a modest post-bridge shift in the development of functional integration. The Öresund Area development towards a bi-national, integrated, functional urban region is in progress, but the progress is much slower than expected. 相似文献
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315.
Optimization of land use structure consists of economic and social and ecological optimization.Applying the minds of system engineering and principles of ecology,this paper presents such thoughts:the optimal forest-coverage rate calculated according to the reality of a district is set as main standard of ecological rationality in the district;through considering the value of ecosystem services of the land with GREEN equivalent(mainly cultivated land and grassland)and based on the rule GREEN equivalent,this paper introduces the area conversion between woodland and cultivated land ,also between woodland and grassland;this paper establishes a multi-dimension controlling model of optimization of land use structure,In addition,a multiobjective linear programming model for optimization of land use structure is designed.In the end,this paper tests and verifies this theory of ecological optimization,taking Qionghai city in Hainan Province as an example. 相似文献
316.
新建水源地如何最优布井,对水源地开采运行具有重大影响。本文介绍了0-1整数规划及其求解方法,并结合一个实际问题进行说明。作者应用0-1整数规划方法建立了北京密怀顺平原区拟建水源地最优布井的地下水管理模型,采用响应矩阵法将地下水模拟模型和管理模型相耦合,运用分支-定界法求出最优井位,并将优化井位与原拟定井位的计算结果进行了对比。结果表明,0-1整数规划能很好地解决最优布井问题,对水源地规划、基坑降水、地下水人工回灌等方面都具有一定的指导意义。 相似文献
317.
The non‐stationary Functional Series time‐dependent autoregressive moving average (TARMA) modelling and simulation of earthquake ground motion is considered. Full Functional Series TARMA models, capable of modelling both resonances and antiresonances, are examined for the first time via a novel mixed parametric/non‐parametric estimation scheme, and critical comparisons with pure TAR and recursive ARMA (RARMA)‐recursive maximum likelihood (RML) adaptive filtering type modelling are made. The study is based upon two California ground motion signals: a 1979 El Centro accelerogram and a 1994 Pacoima Dam accelerogram. A systematic analysis, employing various functional subspaces and model orders, leads to two Haar function based models: a TARMA(2,4)8 model for the El Centro case and a TARMA(6,2)10 model for the Pacoima Dam case. Both models are formally validated and their simulation (synthesis) capabilities are demonstrated via Monte Carlo experiments focusing on important time domain signal characteristics. The Functional Series TAR/TARMA models are shown to achieve parsimony, as well as superior accuracy and simulation capabilities, over their RARMA counterparts. Copyright © 2001 John Wiley & Sons Ltd. 相似文献
318.
VB与Visual Fortran混合语言编程及其在物探化探数值计算中的应用 总被引:1,自引:0,他引:1
作者在本文中详细介绍了VB与Visual Fortran(VB\VF)混合语言编程技术,尤其是对怎样用VB语言调用Fortran动态连接库(DLL)进行了详细的说明。将VB\VF进行混合语言编程一方面可以达到这两种语言的优势互补的目的,另一方面可以再利用前人留下的大量成熟的Fortan程序,避免了重复编程和资源浪费,节约了大量编程时间。混合语言编程在物探化探数值计算中是一种很有前途的编程方法。 相似文献
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320.
This paper is devoted to the numerical reliability and time requirements of the Mixed Finite Element (MFE) and Mixed-Hybrid Finite Element (MHFE) methods. The behavior of these methods is investigated under the influence of two factors: the mesh discretization and the medium heterogeneity. We show that, unlike the MFE, the MHFE suffers with the presence of badly shaped discretized elements. Thereat, a numerical reliability analyzing software (Aquarels) is used to detect the instability of a matrix-inversion code generated automatically by a symbolic manipulator. We also show that the spectral condition number of the algebraic systems furnished by both methods in heterogeneous media grows up linearly according to the smoothness of the hydraulic conductivity. Furthermore, it is found that the MHFE could accumulate numerical errors if large jumps in the tensor of conductivity take place. Finally, we compare running-times for both algorithms by giving various numerical experiments. 相似文献