民族地区农村生产要素市场化的实证分析——以云南省丽江市玉龙县鲁甸乡为例

民族地区农村生产要素市场化水平比较低,阻碍了民族地区农村市场化改革的进程,并直接影响到农民增收。完善农村生产要素市场体系、理顺市场机制、实现生产要素的优化配置是农村市场化改革的关键。文章阐述了农村生产要素市场化改革的重要意义,分析了农村生产要素市场化的制约因素,并以云南省丽江市玉龙县鲁甸乡的实践为例,试图为农村生产要素市场化改革提供启示。     

亚洲发展中国家现代化发展的路径选择与比较——以中国、印度、沙特为考察对象

儒家文化、印度文化和伊斯兰文化构成了亚洲东方文化的主体。在这三大文化圈中,中国、印度和沙特阿拉伯无疑是各自文化圈中最具代表性的国家,从地域上也都是区域性的大国。它们的发展道路的选择和效用在各自区域内都具有明显的示范效应。在迈向现代化的征途中,中国、印度、沙特因现实国情和历史各异,致使实现现代化的方式和选择的社会发展道路存在着明显差别,各具特色。     

干法烟气脱硫渣在建材行业中高技术附加值利用的探讨

文章阐述了目前国内外对干法脱硫渣综合利用的现状,以胶凝材料学以及水泥化学为理论基础,将干法脱硫渣中的物质划分为三类,并提出在充分激发其活性的基础上,对干法脱硫渣进行高技术附加值的利用,并详细阐述了其原理和途径。     

论西部欠发达资源丰富地区经济发展战略的重心转移——以新疆为例

西部欠发达资源丰富地区围绕优势资源实施资源开发,本来是符合经济分工和市场竞争原则的理性选择。但在实践中,又往往容易形成路径依赖,即过于依赖和偏重对自然资源的开发,使潜藏在资源开发中的商品贸易和经济竞争劣势逐渐显露出来。因此,西部必须开拓思路,超越优势资源的束缚,把开发的重心由自然资源转向知识资源,着力实施科教兴国和人才强国战略,而这些正是当前西部最欠缺的也是市场机制难以发挥积极作用的领域,需要政府强力推进和实施。     

Avulsions in a Simulated Large Lowland Braided River

The understanding of the complicated braiding mechanisms in braided rivers is closely related to avulsions. They control the channel generation, migration and disappearance in large lowland braided rivers, and are considered to be the key factor that keeps the river maintaining a dynamic braided pattern. However, their occurring processes and mechanisms are still not well understood due to the lack of detailed measurements with sufficient temporal and spatial data covering multiple bifurcations. In the present study, a numerical model based on the physical process of hydrodynamics and sediment transport is used to simulate the suspended sediment transport and river channel evolution in braided rivers. The model predicted braiding processes are comparable to those observed in nature. Efforts are made to investigate the morphological processes that are key for river braiding. Three types of avulsions observed in natural rivers have been identified in the model predicted river and their evolution processes and controlling factors are examined based on the predicted flow velocity, sediment concentration, bed elevation and sediment size distribution. It was found that, a curving channel bend is the key factor in introducing a constriction avulsion, while the choking avulsion and apex avulsion are controlled by the water surface slope and bed elevation. They are mostly affected by the upstream channel pattern changes.     

A simple permanent deformation model of rockfill materials

Existing experimental results have shown that using a semi-log linear relationship between the permanent volumetric strain and cyclic number underestimates the volumetric deformation of rockfill materials with a large cyclic number, and that the error increases with the confining pressure. The existing permanent deformation models are not suitable for the seismic safety analysis of high dams during strong earthquakes. In this study, a series of large-scale triaxial cyclic loading tests of rockfill materials were performed, and a new permanent deformation model of rockfill materials was developed and validated with three kinds of rockfill materials. The results show that the proposed model can properly reflect the general features of the permanent deformation of rockfill materials. The main features of the model are as follows: (1) relations between the cyclic number and permanent volumetric/shear strain are described by hyperbolic functions, which can avoid underestimating the volumetric deformation occurring during strong earthquakes; (2) the model can capture the effect of the mean effective stress on the permanent volumetric strain, with greater confining pressure correlating to greater permanent volumetric deformation, and the permanent volumetric strain under low confining pressure near the dam crest can be well represented; and (3) the model can reflect the effect of the consolidation stress ratio on the permanent shear strain.     

Numerical analyses of ventilated cavitation over a 2-D NACA0015 hydrofoil using two turbulence modeling methods

The present paper studies the ventilated cavitation over a NACA0015 hydrofoil by numerical methods. The corresponding cavity evolutions are obtained at three ventilation rates by using the level set method. To depict the complicated turbulent flow structure, the filter-based density corrected model(FBDCM) and the modified partially-averaged Navier-Stokes(MPANS) model are applied in the present numerical analyses. It is indicated that the predicted results of the cavitation shedding dynamics by both turbulence models agree fairly well with the experimental data. It is also noted that the shedding frequency and the super cavity length predicted by the MPANS method are closer to the experiment data as compared to that predicted by the FBDCM model. The simulation results show that in the ventilated cavitation, the vapor cavity and the air cavity have the same shedding frequency. As the ventilated rate increases, the vapor cavity is depressed rapidly. The cavitation-vortex interaction in the ventilated cavitation is studied based on the vorticity transport equation(VTE) and the Lagrangian coherent structure(LCS). Those results demonstrate that the vortex dilatation and baroclinic torque terms are highly dependent on the evolution of the cavitation. In addition, from the LCSs and the tracer particles in the flow field, one may see the process from the attached cavity to the cloud cavity.     

平原地区城市湖泊防洪与景观功能协调研究——以枝江市金湖为例

为了使城市湖泊尽可能滞蓄雨洪、发挥景观功能、打造良好的居民亲水空间,以枝江市金湖为例,根据金湖主要泄洪渠道的实际情况,利用Mike 21模型模拟计算汛限水位值,按照景观水位确定大、小洪水工况下合理的水位。在此基础上,提出传统的静态景观水位与改进的动态景观水位两种方案。结果表明:以50年一遇、30年一遇为代表的大洪水工况下合理景观水位为40.7 m,以20年一遇、10年一遇为代表的小洪水工况合理景观水位为41.3 m;静态方案采用50年一遇洪水计算结果为标准执行,将40.7 m作为金湖固定的景观水位;动态方案水位可在41.3~40.7 m之间波动;金湖适宜采用动态景观水位运行方案,水位可在40.7~41.3 m之间波动;根据短期预报及历史监测资料分析后合理调度,将41.3 m作为金湖常水位,确定预测洪水大小后调整水位迎战洪水。据此,可在充分利用水资源的同时有效协调景观高水位需求与防洪之间的矛盾。     

基于改进支持向量机回归的日径流预测模型

日径流预测是水资源优化调度的重要组成部分,日径流预测精度的高低直接影响水资源优化配置的程度。针对日径流序列的特性,研究提出一种改进的支持向量机回归模型,并应用于日径流预测。与基本支持向量机和BP神经网络对比分析的实验结果表明,基于改进支持向量机回归预测模型的日径流预测精度明显高于BP网络,尤其是对于变化剧烈的径流序列表现出较基本支持向量机回归模型更优越的预测性能,为日径流预测分析提供了一种可靠、有效的途径和方法。     

桐子林水电站明渠导流方案优化研究

欠宽阔覆盖层河道采用明渠导流宣泄大流量时,施工度汛所面临的水力学问题突出。对桐子林水电站导流明渠3种布置方案进行了系统模型试验。研究表明:底宽44 m明渠方案出口流速高达17 m/s,消能防冲难度极大,采用钢筋石笼和四面体防护失事风险很高;若在明渠末端增加消力池,由于明渠水流弗氏数Fr1.5,消能效果无法提高,明渠出口流速仍达13 m/s;结合闸坝地基采用地下连续墙加固等措施,可将明渠宽度增加至62 m,明渠出口流速减小至10 m/s,钢筋石笼和四面体稳定性大大提高,能够有效解决明渠出口消能防冲问题。试验表明,采用宽明渠方案是解决大单宽流量明渠出口下游消能防冲的有效方法。