Design of tariff zones in public transportation networks: theoretical results and heuristics

The problem of fair zone design for local public transportation networks is considered. A network model which was introduced by Hamacher and Schöbel in [2] is investigated. We present theoretical results for special transportation networks and heuristic algorithms for the general problem.     

Retention of pesticides and nutrients in a vegetated buffer root zone compared to soil with low biological activity

A laboratory study has been conducted to examine the retention processes of nitrogen and pesticides through vegetated buffer zones compared to bare soil. Soil columns with low biological activity and vegetation columns with normal biological activity were tested. Pesticides frequently used in vegetable production (namely aclonifen, azinphos-methyl, chlorpropham, diazinon, dimethoate, fluazinam, iprodione, linuron, metalaxyl, metamitron, metribuzin and propachlor) equal to 1/50 to 1/5 part of recommended doses, and nutrients equal to 1, 5 and 20 mg N/L and 0.2 mg P/L, were added. The pesticide retention was more than 60% for all pesticides, except dimethoate, with a retention of about 30% in columns with low microbial activity. Biological transformation and plant uptake were important for removal of nitrogen and organic matter. Nitrogen retention was high (over 90%) in vegetation columns. Plant uptake and phosphorus content in soil were important for phosphorus retention.     

一维光子晶体非线性色散特性的分析

从无限周期一维光子晶体的色散关系和有限周期光子晶体的透射系数两个方面,对有限和无限周期光子晶体有效折射率的实部和虚部特性曲线分别进行了计算和分析.结果表明一维光子晶体的色散曲线与弹性电偶极子的经典色散曲线类似,在光子晶体的导带为正常色散,而在禁带呈现反常色散.并且用简约布里渊和扩展布里渊区色散曲线对文献报道中存在的两种矛盾的计算结果进行了理论的探讨.解释了导致对一维光子晶体有效折射率计算存在两种不同结果的原因.     

同步辐射X射线衍射光谱在地带性土壤粘粒矿物研究中的应用

X射线衍射(XRD)光谱是分析土壤粘粒矿物组成的重要手段,但常规XRD分析存在前处理复杂、耗时较长、光谱分辨率低、扫描不充分等问题.为此,该研究依托北京同步辐射装置(BSRF)的4B9A衍射实验站,以我国东部不同气候带(即温带、亚热带、热带)的7种地带性森林土壤(棕色针叶林、暗棕壤、棕壤、黄棕壤、黄壤、赤红壤和砖红壤)...     

Microstructure of Bonding Zones in Laser Clad TiC-reinforced Coating

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Distinguishing between Fraunhofer and Fresnel diffraction by the Young's experiment

Theoretical considerations, simulations and experiments have been carried out to distinguish between Fresnel and the Fraunhofer diffraction regarding the formation of interference patterns by a conventional Young's double-pinhole arrangement with variable separation, which is illuminated by a coherent plane wave. We show that the optical path difference introduced by this setup fits the Fresnel's phase difference between the pinholes. Consequently, it is possible to determine the number of Fresnel zones subtended by a circle centered on one of the pinholes and with radius equals to the pinhole separation. Then, we propose a criterion for distinguishing between Fresnel and Fraunhofer diffraction based on this number of Fresnel zones, which is applicable for diffracting apertures with any shape.     

On Plane-Parallel Separated Flows of an Incompressible Fluid near Flat Boundaries

On the basis of Stokes separated flows, examples of separated flows described by the Navier-Stokes equations of a viscous incompressible fluid are constructed. These flows are represented by series convergent in a certain non-zero neighborhood of a flat contour immersed in the flow. In this neighborhood, the series have the same structure as those for the basic Stokes flows. Examples of the regions in which the series segments chosen give only a slight deviation from the numerical solutions of the Navier-Stokes equations are presented. The comparison between inviscid separated flows (without the no-slip condition on the contour) and viscous flows of the same structure (with the no-slip condition) shows that the viscosity does not play a decisive role in the formation of separation or the type of streamline approach to or departure from the contour.     

层间剪切带法向空间分布定量预报

本文讨论了层间剪切带法向空间分布定量预报问题。文中首先对层间剪切带发育的力学机制进行了再认识, 提出了基于变形破坏程度的分类方案; 引进了构造地质学中的尺度概念; 讨论了影响层间剪切带在法向空间发育分布的因素并建议了相应的考虑方法。之后, 建立了两个模型分别讨论岩石地层“软硬相间”的组合特征和完善型剪切带分区段预报。由此提出了一套实用性强比较可靠的定量预报方法, 最后用该方法对清江高坝洲坝基层间剪切带的分布进行了验证性预报, 取得了较高的精度(精度在70%左右)。