交互式网络三维传感技术在水流动态模型中的应用

利用数字高程模型生成可交互的虚拟现实三维模型.将虚拟现实建模语言与Java脚本相结合,模拟了动态交互的三维河道水流场景.

黄河泥沙与微污染物动态界面作用及去除方法研究框架

受黄河流域的水力条件、多介质环境等因素影响,泥沙与污染物动态界面作用机制复杂。近年来泥沙与污染物相互作用研究主要集中在静态条件下,对动态水流条件及微污染物的关注较少。本文在总结国内外对泥沙与污染物界面作用机制及河流污染物去除方法研究现状的基础上,基于黄河流域高泥沙含量的特殊条件,提出水体中泥沙与污染物动态界面作用机制及同步去除方法的研究框架,揭示开展该研究的关键问题及具体方法,为高沙水体中污染物行为及去除方法研究提供理论支撑。

基于仿水流算法的最短路径问题求解

使用传统算法求解最短路径问题时,收敛速度慢,且求得的路径并不是所有行程的最短路径。为此文章提出一种求解最短路径问题的仿水流算法。该算法结合水流量局部更新和全局动态更新,能够动态调配水流量值,避免算法陷入停滞状态;局部搜索中,对于更优路径的水流使用2-opt方法进行搜索,以此提高收敛速度。仿真实验验证了该算法的有效性,与其他算法相比,仿水流算法收敛速度快,收敛精度高,鲁棒性好,所求的最短路径明显优于传统算法。

短期梯级水电优化调度的逐次逼近法

受到水电站的出库流量的影响,梯级水电站间的水流滞时是动态变化的,如果将水流滞时作为常数考虑,会导致水电优化调度结果的偏差。将水流滞时表示成电站出库流量的函数形式,建立了考虑动态水流滞时的短期梯级水电优化调度模型。动态水流滞的引入,使得短期梯级水电优化调度中的优化变量在大小和时间两个维度上变化,采用常规算法直接求解困难。针对所建立模型的特点,提出了结合逐次逼近法和混合整数线性规划法的求解方案,以逐次逼近法构造了逐步逼近精确水流滞时的迭代流程,迭代流程中每次迭代为一个常规短期梯级水电优化调度问题,采用混合整数线性规划法进行求解。一个两电站测试系统和某8水库的实际梯级水电系统的算例结果表明了所提出模型和方法能够有效提升梯级水电系统的经济效益。

南水北调工程中水力过渡过程的数值模拟

南水北调工程作为中国重大基础设施项目,其水力过渡过程的数值模拟是确保工程安全运行和优化调度的关键手段,本文论点为该数值模拟对理解与控制水流动态、规避潜在风险及提高水资源利用效率至关重要。构建精确数值模型可预判水流在不同工况下的行为,为工程设计和运行维护提供依据,研究结果显示数值模拟在分析水力过渡现象、识别关键节点和优化调度策略优势显著,利于工程长期稳定运行。

城市河道治理工程中生态水利设计理念的运用

城市河道治理工程是推动城市可持续发展的重要措施,而生态水利设计理念的运用是其核心环节。本研究以生态水利设计理念为指导,结合具体的城市河道治理工程实例,详细阐述了生态水利设计在其中的实际应用和重要意义。研究发现,生态水利设计不仅有助于改善城市环境,提高城市居民的生活水平,还有助于实现水资源的综合管理和保护。具体体现在通过生态恢复,建立起多样化的河道生态系统,实现河道的自净功能,有效减少污染;采用自然化的河岸设计,实现河岸稳定,提高河岸的生态价值和景观效果;强调水流动态平衡和泥沙动态平衡的实现,提高河道的防洪能力。研究结果显示,运用生态水利设计理念的城市河道治理工程具有显著的综合效益,能有效推动城市和环境的和谐共生,为未来城市河道治理提供了有益的参考。

某越野车顶盖密封性能特征分析与优化

解决整车的淋雨密封性问题是整车研发、制造过程中的一个系统性、复杂性的工程,然而目前密封的机理与解决方法尚不完善。基于此,文章介绍了一种越野车型漏水问题的研究方法与解决思路,提出了动态水流路径分析法与DOE实验设计结合的策略。对车身结构、相关零部件的密封性能进行分析评估,确定异常水流路径及影响因子,通过正交实验以及均值分析得到最优化的密封条唇边降低高度、硬度、长度参数,并在批量生产过程中进行充分的验证,改善了顶盖间密封系统,将整车的淋雨一次通过率从62.5%提高至99.3%。

数值模拟在银川市地下水资源开采评价中的应用

在研究银川市地下水系统特征的基础上 ,建立了数值模型对地下水位动态进行模拟和预测 ,进而对开采资源作出评价 .

Dynamic Monitoring of Soil Erosion for Upper Stream of Miyun Reservoir in the Last 30 Years

The Revised Universal Soil Loss Equation （RUSLE） was applied to assess the spatial distribution and dynamic properties of soil loss with geographic information system （GIS） and remote sensing （RS） technologies. To improve the accuracy of soil-erosion estimates, a new C-factor estimation model was developed based on land cover and time series normalized difference vegetation index （NDVI） datasets. The new C-factor was then applied in the RUSLE to integrate rainfall, soil, vegetation, and topography data of different periods, and thus monitor the distribution of soil erosion patterns and their dynamics during a 3o-year period of the upstream watershed of Miynn Reservoir （UWMR）, China. The results showed that the new C-factor estimation method, which considers land cover status and dynamics, and explicitly incorporates within-land cover variability, was more rational, quantitative, and reliable. An average annual soil loss in UWMR of 25.68, 21.04, and 16.8o t ha-1 a-1 was estimated for 1990, 2000 and 2010, respectively, corroborated by comparing spatial and temporal variation in sediment yield. Between 2000 and 2010, a 1.38% average annual increase was observed in the area of lands that lost less than 5 t ha-1 a^-1, while during 1990-2000 such lands only increased on average by o.46%. Areas that classified as severe, very severe and extremely severe accounted for 5.68% of the total UWMR in 2010, and primarily occurred in dry areas or grasslands of sloping fields. The reason for the change in rate of soil loss is explained by an increased appreciation of soil conservation by developers and planners. Moreover,we recommend that UWMR watershed adopt further conservation measures such as terraced plowing of dry land, afforestation, or grassland enclosures as part of a concerted effort to reduce on-going soil erosion.

Salt-Water Dynamics in Soils:Ⅲ.Effect of Crop Planting

Through a simulation test conducted with soil columns (61.8cm in diameter) in field condition,effect of crop planting upon the regulation of salt-water dynamics in soils was studied by monitoring of salt-water dynamics in situ,using soil salinity sensors and tensiometers.The results indicated that the amount of water absorbed by crops from the soil was generally larger than the decrement of water consumption from soil surface evaporation reduced by the crop covering the soil surface and improving the soil structure,therefore,under the conditions of crop growing and non-irrigation,water content in soil profile was less than that without crop growing,and the gradient of negative pressure of soil water in soil profile especially in the root zone was enlarged,thus causing the water flowing from subsoils into root zone and increasing the groundwater moving upwards into soil layer via capillary rise,so that the groundwater evaporation increased.Consequently,under the condition of crop growing,the salt was mainly accumulated towards the root zone rather than to the top soil.the accumulating rate of salt in groundwater via capillary rise of soil water to subsoils was increased thereby.

Multi-model Predictive Control of Ultra-supercritical Coal-fired Power Unit

The control of ultra-supercritical(USC) power unit is a difficult issue for its characteristic of the nonlinearity, large dead time and coupling of the unit. In this paper, model predictive control(MPC) based on multi-model and double layered optimization is introduced for coordinated control of USC unit. The linear programming(LP) combined with quadratic programming(QP) is used in steady optimization for computation of the ideal value of dynamic optimization. Three inputs(i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs(i.e. load, main steam temperature and main steam pressure). The step response models for the dynamic matrix control(DMC) are constructed using the three inputs and the three outputs. Piecewise models are built at selected operation points. Double-layered multi-model predictive controller is implemented in simulation with satisfactory performance.

Comparative experimental investigation of chemical grouting into a fracture with flowing and static water

We present a series of experimental tests on chemical grouting into a fracture with flowing and static water,using a transparent fracture grouting experimental device.Variations of seepage pressure and grout propagation were compared in our investigation.The results show that flowing water results in drops of seepage pressure,development of penetration radii in the upstream side and drops of propagation area during the same period,compared with grouting in static water.The propagation area in static water is always round before grouts reach the joint boundaries.However,the propagation shape changes from round to an elliptic shape for grouting into a fracture with flowing water.A theoretical model for the grout penetration radius in a fracture considering flowing velocity was developed and validated by our experimental results.These results are helpful in improving understanding of fracture grouting mechanism and in guiding engineering practices.

Quality Evaluation and Its Application to Surface Water Ecosystem Based on Maximum Flux Principle

Based on the maximum flux principle(MFP),a water quality evaluation model for surface water ecosystem is presented by using self-organization map(SOM) neural network simulation algorithm from the aspect of systematic structural evolution.This evaluation model is applied to the case of surface water ecosystem in Xindu District of Chengdu City in China.The values reflecting the water quality of five cross-sections of the system at different developing stages are obtained,with stable values of 1.438,2.952,1.86...

Ecosystem health evaluation system of the water-fluctuating zone in the Three Gorges Area

This paper discribes the definition of ecosystem health for the water-level flutuation zone of the Three Gorges Region and puts forward an evaluation system involving indicators in three groups: 1) structural indicators comprise slope, biodiversity, environmental capacity, stability, restoration ability and damage situation; 2) functional indicators including probability of geological hazard, erosion rate, habitat rate, land use intension and days of tourist season; 3) environmental indicatiors made up of population quality, potential intension of human, ground water quality, ambient air quality, wastewater treatment rate, pesticide use rate, fertilizer use rate, environmental management and public participation. In the design of the system, the subject zone is regarded as the type similar to wetland and the impacts of human activities on the zone are attached great importance to.

Effects of Moisture on Rheological Properties of PAV Aged Asphalt Binders

For the most coastal areas where the air is very humid,study on the effect of humidity on the performance of asphalt has its practical significance.However,limited research has been done to investigate the effect of humidity on rheological properties of asphalt.In this study,asphalt binders were aged in the pressure aging vessel(PAV)under different conditions of moisture and aging time.Then Dynamic Shear Rheometer(DSR)and Bending Beam Rheometer(BBR)measurements were conducted to obtain the parameters relating to the complex modulus,phase angle,failure temperature,and creep stiffness.It was found that the low temperature performance decreased as evidenced by the results of the creep stiffness.While there were no significant differences among conditioned binders based on complex modulus G*and phase angleδ,it was found that theδvalue increased when the humidity increased from 0% to 80% ,and then theδvalue decreased when the humidity increased to 100% .In addition,the results of the failure temperature indicated that the humidity of 80% would be a critical point for the high temperature performance of the asphalt binders.

Study on productivity of horizontal wells with segmental perforation based on pseudo steady-state flow

Segmental perforation is widely used for horizontal wells. However,the flow of fluid in porous media is a complex problem. Using the Fourier transform,principle of potential superposition,trigonometric function transform,asymptotic analyses,a pressure solution of a pseudo steady-state flow model in 3D circular-boxed media has been established. Comparing with the productivity of vertical wells,an equivalence radius model can be obtained. Based on the model,a method of evaluating the productivity of segmental perforation horizontal well is presented by means of principle of superposition. It shows that the equivalence radius is different for various positions of horizontal wells; the output of both ends of horizontal wells is greater than the others under the same length of perforation interval; it is more important to obtain high productivity by increasing the length of perforation interval than enlarging the spacing between perforation intervals. The result of this research can be used to ascertain the yield of each perforated interval.

A Parallel Search System for Dynamic Multi-Objective Traveling Salesman Problem

This paper introduces a parallel search system for dynamic multi-objective traveling salesman problem. We design a multi-objective TSP in a stochastic dynamic environment. This dynamic setting of the problem is very useful for routing in ad-hoc networks. The proposed search system first uses parallel processors to identify the extreme solutions of the search space for each ofk objectives individually at the same time. These solutions are merged into the so-called hit-frequency matrix E. The solutions in E are then searched by parallel processors and evaluated for dominance relationship. The search system is implemented in two different ways master-worker architecture and pipeline architecture.

A distributed scheme developed for eco-hydrological modeling in the upper Heihe River

Modeling the hydrological processes at catchment scale requires a flexible distributed scheme to represent the catchment to- pography, river network and vegetation pattern. This study has developed a distributed scheme for eco-hydrological simulation in the upper Heihe River. Based on a 1 km x 1 km grid system, the study catchment is divided into 461 sub-catchments, whose main streams form the streamflow pathway. Furthermore, a 1 km grid is represented by a number of topographically similar ＂hillslope-valley＂ systems, and the hillslope is the basic unit of the eco-hydrological simulation. This model is tested with a simplified hydrological simulation focusing on soil-water dynamics and streamflow routing. Based on a 12-year simulation from 2001 to 2012, it is found that variability in hydrological behavior is closely associated with climatic and landscape condi- tions especially vegetation types. The subsurface and groundwater flows dominate the total river runoff. This implies that the soil freezing and thawing process would significantly influence the runoff generation in the upper Heihe basin. Furthermore, the runoff components and water balance characteristics vary among different vegetation types, showing the importance of coupling the vegetation pattern into catchment hydrological simulation. This paper also discusses the model improvement to be done in future study.

Progress on shelf and slope circulation in the northern South China Sea

Influenced by the seasonally reversed monsoons, water exchange through straits, and topography, the shelf and slope circulation in the northern South China Sea(NSCS) is complex and changeable. The typical current system in the NSCS consists of the slope current, South China Sea warm current(SCSWC), coastal current, and associated upwelling(in summer) and downwelling(in winter). This paper reviews recent advances in the study of NSCS shelf and slope circulation since the 1990 s,and summarizes the roles of Kuroshio intrusion, the monsoons, topography, and the buoyancy effect of the Pearl River plume in the shelf and slope current system of the NSCS. We also point out some potential scientific issues that require further study, such as the dynamic connection between the internal basin and shelf areas of the NSCS, the persistence of the SCSWC in winter, the temporo-spatial characteristics of downwelling during winter in the NSCS, and its material and energy transport.

Numerical modeling of regional groundwater flow in the Heihe River Basin,China:Advances and new insights

Numerical groundwater modeling is an effective tool to guide water resources management and explore complex groundwater-dependent ecosystems in arid regions.In the Heihe River Basin(HRB),China’s second largest inland river basin located in arid northwest China,a series of groundwater flow models have been developed for those purposes over the past 20 years.These models have elucidated the characteristics of groundwater flow systems and provided the scientific basis for a more sustainable management of groundwater resources and ecosystem services.The first part of this paper presents an overview of previous groundwater modeling studies and key lessons learned based on seven different groundwater models in the middle and lower HRB at sub-basin scales.The second part reviews the rationale for development of a regional basin-scale groundwater flow model that unifies previous sub-basin models.In addition,this paper discusses the opportunities and challenges in developing a regional groundwater flow model in an arid river basin such as the HRB.