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311.
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.
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   
313.
根据条件平差原理,推导出三维导线平差的数学模型,并在VB下实现平差程序设计。  相似文献   
314.
热压金刚石工具胎体是用粉末冶金法形成的金属基复合材料,介绍了规划设计法研究的要点。  相似文献   
315.
Optimization of Land Use Structure Based on Ecological GREEN Equivalent   总被引:1,自引:0,他引:1  
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.
0-1整数规划在水源地开采井最优布局中的应用研究   总被引:4,自引:0,他引:4       下载免费PDF全文
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.
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   
319.
基于OOP技术的地图符号制作工具的设计与实现   总被引:10,自引:2,他引:10  
分析了地图符号构图的规律性,提出了应用OOP技术描述地图符号的方法。对基于OOP技术设计的地图符号制作工具的实现方法作了简要介绍,分析了OOP技术设计地图符号的优越性。将地图符号的特征描述与特征再现分解开来,符号的特征描述通过对象的成员变量记录,并保存在符号库文件中。符号特征再通过对象的成员函数实现,使得符号再现可以与符号信息记录分离,符号失败与符号调用在不同系统中进行,提高了系统的整体性能。  相似文献   
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   
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