黄土丘陵区不同土地利用方式下土壤水分入渗的对比试验

为更好地掌握黄土丘陵区不同土地利用方式下的土壤水分入渗性能,采用双环法和人工降雨法,分别对陕西省延安市燕沟流域林地、草地、农地3种土地利用方式的土壤水分入渗过程进行了对比试验。结果表明:双环法能较好的反映水向土中的入渗过程;而人工降雨法可以较为真实地反映天然降雨过程中雨水向土中的入渗过程, 两者有很大的不同,主要表现在土壤水分的入渗速率变化过程方面。前者测定的土壤水分入渗速率主要受制于土壤的物理性状,而后者:不但与土壤物理性状有关,还与降雨强度有较密切的关系。在人工模拟短历时暴雨条件下, 对于林地和荒坡草地,土壤水分入渗速率有随雨强增大而增大的趋势,而对于裸耕农地,随着雨强的增大,土壤水分入渗速率有降低的趋势。

水文条件对紫色土坡面土壤侵蚀及养分流失的影响

采用人工模拟降雨试验,研究水文条件对紫色土坡面土壤侵蚀及氮和磷养分流失的影响。试验处理包括2个施肥水平(低肥和高肥水平),4个水文条件(自由下渗、土壤水分饱和、壤中流、壤中流+降雨)和一个降雨强度(60 mm/h,历时60 min)。结果表明:壤中流+降雨和土壤水分饱和条件下的土壤侵蚀量分别是自由下渗条件下的3.1和1.7倍,同自由下渗相比,壤中流、壤中流+降雨和土壤水分饱和条件下,地表径流中NO3-N、HPO4-P的浓度和流失量有显著增加;低肥水平条件下,自由下渗、土壤水分饱和、壤中流和壤中流+降雨地表径流中,NO3-N的浓度分别是0.88、58.90、698.41和87.80 mg/L,对应水文条件下地表径流中,HPO4-P的浓度分别是0.252、0.322、0.811和0.383 mg/L,高肥水平条件下,径流中的NO3-N和HPO4-P的浓度也有相同的趋势;土壤水分饱和条件下,地表径流中NO3-N和HPO4-P的流失量分别是自由下渗条件下的27~39和1.3倍,壤中流+降雨条件下,地表径流中NO3-N和HPO4-P的流失量分别是自由下渗条件下的100~114和1.5~1.7倍,同时,壤中流+降雨和土壤...

黄土坡面水力学特征参数与土壤侵蚀量间关系研究

通过室内人工降雨模拟试验,研究黄土坡面水流的水力学特征参数与土壤侵蚀量间的关系。结果表明:随着放水流量的增加,出口断面平均流速、雷诺数在逐渐增大,弗劳德数在逐渐减小,坡面流流态也从层流状态逐渐过渡到紊流状态,当放水流量在10.1~19.9 L/min范围内时,坡面水流的流态为层流与紊流之间的混和状态;出口断面的平均流速随着放水流量的增加而增大,二者之间呈良好的幂函数关系;黄土坡面的累计泥沙侵蚀总量随着雷诺数的增加而增大,二者呈幂函数关系;单宽土壤侵蚀产沙量与雷诺数之间拟合关系的好坏受雷诺数取值的影响,当雷诺数的值在临界雷诺数(取500)附近时,单宽土壤侵蚀产沙量与雷诺数之间的负相关性良好。研究结果不仅可以揭示土壤侵蚀水动力过程的内在机制,而且对黄土高原地区生态环境建设具有重要的现实意义。

Layout Design and Optimization of RF Spiral Inductors on Silicon Substrate

The effects of key geometrical parameters on the performance of integrated spiral inductors are investigated with the 3D electromagnetic simulator HFSS. While varying geometrical parameters such as the number of turns （N）,the width of the metal traces （W）,the spacing between the traces （S）,and the inner diameter （ID）, changes in the performance of the inductors are analyzed in detail. The reasons for these changes in performance are presented. Simulation results indicate that the performance of an integrated spiral inductor can be improved by optimizing its layout. Some design rules are summarized.

SR型野外人工模拟降雨装置

SR型人工降雨装置是一种多喷头、多单元组合式的间歇降雨装置。选用目前国内外较理想的喷头 ,在喷头处辅以可改变喷头降水方式的机械传动装置 ,以间歇方式降雨来满足其降雨强度 ,雨滴直径大小及其分布与自然降雨相似。每个单元的有效降雨面积为 2 m× 5 m;如果 4个单元组合成 ,其长度可增加 4倍 ,有效降雨面积即 2 m× 2 0 m。装置采用轻型铝合金材料制成 ,结构简单 ,易于安装拆卸 ,适用于野外工作。

施加PAM的坡地降雨入渗过程及其模型研究

作为一种新型高效的土壤结构改良剂 PAM,在一定条件下能显著地提高土壤入渗能力 ,减小坡面径流。采用室内人工模拟降雨试验 ,研究了不同 PAM覆盖度下降雨产流随时间的动态变化及其与雨强、坡度的关系 ,以及入渗率随时间的变化规律 ,分析了 PAM、坡度、雨强对入渗率的影响。结果表明 ,地表施加 PAM后土壤的入渗率及稳定入渗率都比未施 PAM显著提高。通过对比施加 PAM后 Kostiakov入渗模型与 Horton入渗模型的显著性 ,表明 Horton入渗公式的适用性更好

北太平洋低纬度西边界流的时空特征和变异规律研究

北太平洋低纬度西边界流连接着太平洋热带环流和副热带环流，对于世界大洋经向质量、热量和盐量输送起着重要的作用，对北赤道流（NEC）、源区黑潮（KC）和棉兰老流（MC）的时空特征和变异规律进行研究，对认识北太平洋西边界流海洋在全球气候系统中的作用具有重要的理论和实践意义。 本文利用1957-2006年共50年的涡解高分辨率OFES（OGCM for the Earth Simulator）海洋模式资料，对北太平洋低纬度西边界流的时空特征和变异规律进行了分析，结果表明： （1）涡解高分辨率的OFES模式数据结果较SODA能更好地刻画NMK流系三维空间结构的分布特征；黑潮源区涡结构的变化，MUC、 LUC及NEC下的东向流也得到了较好的刻画；其空间结构与实测结果相吻合。 （2）北太平洋低纬度西边界流NMK流系流量具有明显的季节、年际和年代际变化，NEC、KC和MC流量的变化周期频谱较宽,主要为3－6个月的季节振荡和2-7年左右ENSO尺度周期以及10年以上周期的年代际变化。MC主要表现为准两年周期振荡。 （3）NEC、MC流量变化表现为单峰型分布，春季最大（5月），秋季最小（11月）；KC流量的变化为双峰型，大值出现在春季和夏末秋初，春季最大（4月），秋季次之，冬季最小（1月）。在季节时间尺度上，NEC、MC流量同相变化，除冬季外，KC与MC输运反向。 （4） 在年际时间尺度上，受北赤道流流量变化的影响，NEC与KC、MC流量之间为正相关关系；KC与MC分配量（北赤道流向北、向南的经向分配量）之间则为强的负相关关系，其年际异常变化与NEC分叉位置的变化和冷、暖ENSO事件发生密切相关。分叉位置偏北（南）时，KC分配量小（大）而MC分配量大（小）；在El Nino年，KC分配量小，MC分配量大，La Nina年情况则刚好相反。 （5）在年代际时间尺度上，在70年代末气候跃变以后，NEC、KC和MC流量明显减少，NMK环流系统减弱。NEC的减弱主要受上世纪80年代以后ENSO暖事件发生频率和强度的增加所影响，而KC和MC的减弱则主要受NEC减弱控制。同时发现，NEC分叉位置存有明显的年代际变化，在气候跃变以后有长期偏北的趋势，受其影响，与之相对应的是北赤道流向南经向分配量的增加和向北流量分配率的减少。 关键词：北太平洋，低纬度西边界流，北赤道流分叉，ENSO

网络机器人遥操作系统设计与实现

本文在分析了网络环境下机器人遥操作系统的结构的基础上,介绍了一套基于网络的移动机器人遥操作实验系统的设备组成及硬软件结构的设计和实现。系统设计简洁有效,网络虚拟机的设计和使用则极大地方便了遥操作研究的开展。

基于循环抑制CPG模型控制的蛇形机器人三维运动

具有三维运动能力和独特的节律运动方式,使生物蛇能在复杂的地形环境中生存.大多数动物节律运动是由中央模式发生器(Centralpatterngenerator,CPG)控制的.以此为理论依据,首次以循环抑制建模机理构建蛇形机器人组合关节运动控制的CPG模型.证明该模型是节律输出型CPG中微分方程维数最少的.采用单向激励方式连接该类CPG构建蛇形机器人三维运动神经网络控制体系,给出该CPG网络产生振荡输出的必要条件.应用蛇形机器人动力学模型仿真得到控制三维运动的CPG神经网络参数,利用该CPG网络的输出使“勘查者”成功实现三维运动.该结果为建立未探明的生物蛇神经网络模型提供了一种全新的方法.

基于循环抑制CPG模型的蛇形机器人控制器

依据生物利用中央模式发生器(Central pattern generator,CPG)的自激行为产生有节律的协调运动适应多种环境,基于循环抑制CPG建模理论设计了蛇形机器人CPG控制器模型,分析了单个神经元、循环抑制CPG以及该控制器模型的稳定性,并把该控制器应用到一个结合蛇形机器人“勘查者-Ⅰ”动力学特性的仿真模型,得到了实现蜿蜒运动的CPG控制器参数,进而研究了调节S波个数、身体构形曲率、蜿蜒运动速度以及运动轨迹曲率的CPG控制器参数设定策略。此外,“勘查者-Ⅰ”应用该CPG控制器的输出成功实现了蜿蜒运动。该研究结果为设计人工CPG控制器提供了一个可行的方法。

排爆作业机器人模拟训练系统研究

介绍了一种排爆机器人模拟训练系统.该系统提供了友好的人机交互界面,使操作人员可以进行各种模拟训练,并提高操作水平.重点介绍了该模拟训练系统的体系结构及关键实现技术,包括排爆机器人及其工作环境的建模方法、机器人运动学和动力学简化模型、碰撞检测和技能评定等.通过实验,证明了该模拟训练系统的可行性和有效性.

基于模糊多目标遗传算法的飞行器模拟件结构参数优化

空间飞行器模拟件的设计是一个具有约束的多目标多准则优化问题。本文在建立空间飞行器模拟件参数优化的数学模型的基础上,将模糊多目标决策理论用于飞行器模拟件的结构参数优化,提出了一种新的模糊评价指数。结构参数优化的结果已经用于某试验系统。

地下水流动数值模拟的并行计算方法研究

Numerical modeling of groundwater is very important for understanding groundwater flow and solving hydrogeological problem. Today, groundwater studies require massive model cells and high calculation accuracy, which are beyond single-CPU computer’s capabilities. With the development of high performance parallel computing technologies, application of parallel computing method on numerical modeling of groundwater flow becomes necessary and important. Using parallel computing can improve the ability to resolve various hydro-geological and environmental problems. In this study, parallel computing method on two main types of modern parallel computer architecture, shared memory parallel systems and distributed shared memory parallel systems, are discussed. OpenMP and MPI (PETSc) are both used to parallelize the most widely used groundwater simulator, MODFLOW. Two parallel solvers, P-PCG and P-MODFLOW, were developed for MODFLOW. The parallelized MODFLOW was used to simulate regional groundwater flow in Beishan, Gansu Province, which is a potential high-level radioactive waste geological disposal area in China. 1. The OpenMP programming paradigm was used to parallelize the PCG (preconditioned conjugate-gradient method) solver, which is one of the main solver for MODFLOW. The parallel PCG solver, P-PCG, is verified using an 8-processor computer. Both the impact of compilers and different model domain sizes were considered in the numerical experiments. The largest test model has 1000 columns, 1000 rows and 1000 layers. Based on the timing results, execution times using the P-PCG solver are typically about 1.40 to 5.31 times faster than those using the serial one. In addition, the simulation results are the exact same as the original PCG solver, because the majority of serial codes were not changed. It is worth noting that this parallelizing approach reduces cost in terms of software maintenance because only a single source PCG solver code needs to be maintained in the MODFLOW source tree. 2. P-MODFLOW, a domain decomposition–based model implemented in a parallel computing environment is developed, which allows efficient simulation of a regional-scale groundwater flow. The basic approach partitions a large model domain into any number of sub-domains. Parallel processors are used to solve the model equations within each sub-domain. The use of domain decomposition method to achieve the MODFLOW program distributed shared memory parallel computing system will process the application of MODFLOW be extended to the fleet of the most popular systems, so that a large-scale simulation could take full advantage of hundreds or even thousands parallel processors. P-MODFLOW has a good parallel performance, with the maximum speedup of 18.32 (14 processors). Super linear speedups have been achieved in the parallel tests, indicating the efficiency and scalability of the code. Parallel program design, load balancing and full use of the PETSc were considered to achieve a highly efficient parallel program. 3. The characterization of regional ground water flow system is very important for high-level radioactive waste geological disposal. The Beishan area, located in northwestern Gansu Province, China, is selected as a potential site for disposal repository. The area includes about 80000 km2 and has complicated hydrogeological conditions, which greatly increase the computational effort of regional ground water flow models. In order to reduce computing time, parallel computing scheme was applied to regional ground water flow modeling. Models with over 10 million cells were used to simulate how the faults and different recharge conditions impact regional ground water flow pattern. The results of this study provide regional ground water flow information for the site characterization of the potential high-level radioactive waste disposal.

石油二次运移的物理与数值模拟实验及其应用

Facing the problems met in studies on predominant hydrocarbon migration pathways, experiments and numerical simulating were done in this thesis work to discuss the migration mechanisms. The aim is to analyze quantitatively the pathway pattern in basin scale and to estimate the hydrocarbon loss on the pathway that offer useful information for confirming the potential hydrocarbon accumulation. Based on our understandings on hydrocarbon migration and the fluid dynamic theory, a series of migration experiments were designed to observe the phenomena where kerosene is used as draining phase driven only by buoyancy force that expulses pore water. These experiments allow to study the formation of migration pathways, the distribution of non-wetting oil along these pathways, and the re-utilizing of previously existing pathways marked by residual traces etc. The types of pattern for migration pathways may be characterized by a phase diagram using two dimensionless numbers: the capillary number and the Bond number. The NMR technique is used to measure the average saturation of residual oil within the pathways. Based our experiment works and percolation concept, a numerical simulation model were proposed and realized. This model is therefore called as BP (Buoyancy Percolation) simulator, since buoyancy is taken as the main driving force in hydrocarbon migration. To make sure that BP model is applicable to simulate the process of oil secondary migration, the experimental phenomena are compared with those simulated with BP model by fractal method, and the result is positive. After then, we use BP simulator to simulate the process of migration of oil in the porous media saturated with water at different scale. And the results seem similar to those cited in literatures. In addition, our software is applied in Paris basin to predict the pathway of hydrocarbon migration happened in the Middle Jurassic reservoirs. It is found that the results obtained with our BP model are generally agree with Hindle (1997) and Bekeles'(1999), but our simulated migration pathway pattern and migration direction seem more reasonable than theirs.

单（多）井抽灌对浅部地温场的影响研究

The technique of energy extraction using groundwater source heat pumps, as a sustainable way of low-grade thermal energy utilization, has widely been used since mid-1990's. Based on the basic theories of groundwater flow and heat transfer and by employing two analytic models, the relationship of the thermal breakthrough time for a production well with the effect factors involved is analyzed and the impact of heat transfer by means of conduction and convection, under different groundwater velocity conditions, on geo-temperature field is discussed.A mathematical model, coupling the equations for groundwater flow with those for heat transfer, was developed. The impact of energy mining using a single well system of supplying and returning water on geo-temperature field under different hydrogeological conditions, well structures, withdraw-and-reinjection rates, and natural groundwater flow velocities was quantitatively simulated using the finite difference simulator HST3D. Theoretical analyses of the simulated results were also made. The simulated results of the single well system indicate that neither the permeability nor the porosity of a homogeneous aquifer has significant effect on the temperature of the production segment provided that the production and injection capability of each well in the aquifers involved can meet the designed value. If there exists a lower permeable interlayer, compared with the main aquifer, between the production and injection segments, the temperature changes of the production segment will decrease. The thicker the interlayer and the lower the interlayer permeability, the longer the thermal breakthrough time of the production segment and the smaller the temperature changes of the production segment. According to the above modeling, it can also be found that with the increase of the aquifer thickness, the distance between the production and injection screens, and/or the regional groundwater flow velocity, and/or the decrease of the production-and-reinjection rate, the temperature changes of the production segment decline. For an aquifer of a constant thickness, continuously increase the screen lengths of production and injection segments may lead to the decrease of the distance between the production and injection screens, and the temperature changes of the production segment will increase, consequently.According to the simulation results of the single well system, the parameters, that can cause significant influence on heat transfer as well as geo-temperature field, were chosen for doublet system simulation. It is indicated that the temperature changes of the pumping well will decrease as the aquifer thickness, the distance between the well pair and/or the screen lengths of the doublet increase. In the case of a low permeable interlayer embedding in the main aquifer, if the screens of the pumping and the injection wells are installed respectively below and above the interlayer, the temperature changes of the pumping well will be smaller than that without the interlay. The lower the permeability of the interlayer, the smaller the temperature changes. The simulation results also indicate that the lower the pumping-and-reinjection rate, the greater the temperature changes of the pumping well. It can also be found that if the producer and the injector are chosen reasonably, the temperature changes of the pumping well will decline as the regional groundwater flow velocity increases. Compared with the case that the groundwater flow direction is perpendicular to the well pair, if the regional flow is directed from the pumping well to the injection well, the temperature changes of the pumping well is relatively smaller.Based on the above simulation study, a case history was conducted using the data from an operating system in Beijing. By means of the conceptual model and the mathematical model, a 3-D simulation model was developed and the hydrogeological parameters and the thermal properties were calibrated. The calibrated model was used to predict the evolution of the geo-temperature field for the next five years. The simulation results indicate that the calibrated model can represent the hydrogeological conditions and the nature of the aquifers. It can also be found that the temperature fronts in high permeable aquifers move very fast and the radiuses of temperature influence are large. Comparatively, the temperature changes in clay layers are smaller and there is an obvious lag of the temperature changes. According to the current energy mining load, the temperature of the pumping wells will increase by 0.7°C at the end of the next five years. The above case study may provide reliable base for the scientific management of the operating system studied.