A game theory model of urban public traffic networks

We have studied urban public traffic networks from the viewpoint of complex networks and game theory. Firstly, we have empirically investigated an urban public traffic network in Beijing in 2003, and obtained its statistical properties. Then a simplified game theory model is proposed for simulating the evolution of the traffic network. The basic idea is that three network manipulators, passengers, an urban public traffic company, and a government traffic management agency, play games in a network evolution process. Each manipulator tries to build the traffic lines to magnify its “benefit”. Simulation results show a good qualitative agreement with the empirical results.     

随机平衡设计傅里叶振幅敏感性分析方法和拓展傅里叶振幅敏感性分析方法在陆面过程模式敏感性分析中的应用探索

探讨了随机平衡傅里叶振幅敏感性分析方法(RBD-FAST)和扩展傅里叶振幅敏感性分析方法(EFAST)在陆面过程模式参数敏感性研究中的应用. 试验中使用通用陆面过程模式(CoLM)和通榆退化草地2008年夏季观测资料, 针对陆气相互作用中重要的要素: 感热通量(SH)、潜热通量(LH)、地表温度(ST), 2 m气温(T2m)和2 m湿度(Q2m), 分析了11 个参数(土深、1–5层黏土比率、孔隙度、最大露水厚度、50%植物根深、地表空气粗糙度和冠层下土壤拖曳系数)的敏感性大小. 结果表明, RBD-FAST和EFAST对参数的一阶敏感性检验结果较为一致且与之前的研究结果类似, EFAST方法还可以得到考虑了参数间相互作用的整体敏感性. RBD-FAST的优势主要表现为在极大地减少了计算消耗机的同时, 一次取样即可计算所有参数的一阶敏感性, 而EFAST的优势则在于通盘考虑了参数之间的相互影响, 可以得到更为合理的整体敏感性序列. 针对不同需求, 选择使用这两种敏感性分析方法, 有助于提高陆面过程模式参数化方案的改进效率.     

Characterisation of multiple conducting permeable objects in metal detection by polarizability tensors

Realistic applications in metal detection involve multiple inhomogeneous‐conducting permeable objects, and the aim of this paper is to characterise such objects by polarizability tensors. We show that, for the eddy current model, the leading order terms for the perturbation in the magnetic field, due to the presence of N small conducting permeable homogeneous inclusions, comprises of a sum of N terms with each containing a complex symmetric rank 2 polarizability tensor. Each tensor contains information about the shape and material properties of one of the objects and is independent of its position. The asymptotic expansion we obtain extends a previously known result for a single isolated object and applies in situations where the object sizes are small and the objects are sufficiently well separated. We also obtain a second expansion that describes the perturbed magnetic field for inhomogeneous and closely spaced objects, which again characterises the objects by a complex symmetric rank 2 tensor. The tensor's coefficients can be computed by solving a vector valued transmission problem, and we include numerical examples to illustrate the agreement between the asymptotic formula describing the perturbed fields and the numerical prediction. We also include algorithms for the localisation and identification of multiple inhomogeneous objects.     

Entropy of the Land Parcel Mosaic as a Measure of the Degree of Urbanization

Quantifying the urbanization level is an essential yet challenging task in urban studies because of the high complexity of this phenomenon. The urbanization degree has been estimated using a variety of social, economic, and spatial measures. Among the spatial characteristics, the Shannon entropy of the landscape pattern has recently been intensively explored as one of the most effective urbanization indexes. Here, we introduce a new measure of the spatial entropy of land that characterizes its parcel mosaic, the structure resulting from the division of land into cadastral parcels. We calculate the entropies of the parcel areas’ distribution function in different portions of the urban systems. We have established that the Shannon and Renyi entropies R0 and R1/2 are most effective at differentiating the degree of a spatial organization of the land. Our studies are based on 30 urban systems located in the USA, Australia, and Poland, and three desert areas from Australia. In all the cities, the entropies behave the same as functions of the distance from the center. They attain the lowest values in the city core and reach substantially higher values in suburban areas. Thus, the parcel mosaic entropies provide a spatial characterization of land to measure its urbanization level effectively.     

干旱区绿洲遥感技术研究

根据实际调查的结果，结合相关图件资料，设计了监督与非监督算法相结合的新的分类器，研究了典型绿洲策勒县土地覆盖动态变化的特征及分布规律。在揭示这些规律之前，利用地面控制点和最大互相关法对三个不央时期（1977年，1990年，1998年）的多源卫星遥感数据（MSS，HRV，TM）进行了精确配准，编制了策勒地区不同年代的土地分类类型图及类型动态变化图，从自然和人文因素两个方面分析探讨了荒漠化发展的趋势。     

山地农业气候与山地生态经济

本文 以浙江山 地为例探讨 了农业气候与山 地生态系统第一性生产力、生态系统的 顺向和 逆向演替以及山 地生态 经济 发展 等的关系.     

因子分析法在土地整理后效益分析与评价中的应用

讨论土地整理后的效益分析与评价,首先建立了土地整理后的综合效益评价指标体系,然后根据土地整理项目工程的实际数据,给出了土地整理后的效益表示．最后应用因子分析法,给出了土地整理后的效益评价．     

坡面侵蚀形态转变过程的REE示踪法研究

利用REE元素示踪法，采取沿坡面垂直分层布设的新的试验布设方法，通过室内模拟降雨试验，研究了次降雨条件下坡面侵蚀形态的转变过程和细沟的发育发展过程。研究结果表明，降雨初期坡面以面蚀为主，细沟出现后，坡面侵蚀将加快加剧；随着降雨时间的延续，累积面蚀量和细沟累积侵蚀量都将逐渐增加，后者的增加速率大于前者，面蚀所占总侵蚀量的百分比随降雨时间呈曲线形式逐渐递减，细沟侵蚀则逐渐增加；试验结束时细沟侵蚀量分别为面蚀量的4—5倍。本研究为定量区分片蚀和细沟侵蚀量以及坡面侵蚀过程中片蚀向细沟侵的转变以细胞侵蚀发生、发育提供了新的思路和解决途径。     

The ethnobotanical,phytochemistry and pharmacological activities of Psidium guajava L.

Psidium guajava L., commonly known as guava is an important tropical food plant with diverse medicinal values. In traditional medicine, it is used in the treatment of various diseases such as diarrhoea, diabetes, rheumatism, ulcers, malaria, cough, and bacterial infections. The aim of this review is to provide up-to-date information on the ethnomedicinal uses, bioactive compounds, and pharmacological activities of P. guajava with greater emphasis on its therapeutic potentials. The bioactive constituents extracted from P. guajava include phytochemicals (gallic acid, casuariin, catechin, chlorogenic acid, rutin, vanillic acid, quercetin, syringic acid, kaempferol, apigenin, cinnamic acid, luteolin, quercetin-3-O-α-L-arabinopyranoside, morin, ellagic acid, guaijaverin, pedunculoside, asiastic acid, ursolic acid, oleanolic acid, methyl gallate and epicatechin) and essential oils (limonene, trans-caryophyllene, α-humulene, γ-muurolene, selinene, caryophyllene oxide, bisabolol, isocaryophyllene, δ-cadinene, α-copaene, α-cedrene, β-eudesmol, α-pinene, β-pinene, β-myrcene, linalool, α-terpineol and eucalyptol). In vitro and in vivo studies demonstrated that P. guajava possesses pharmacological activities such as antidiabetic, antidiarrhoeal, hepatoprotective, anticancer, antioxidant, anti-inflammatory, antiestrogenic, and antibacterial activities which support its traditional uses. The exhibited pharmacological activities reported may be attributed to the numerous bioactive compounds present in different parts of P. guajava. Based on the beneficial effects of P. guajava as well as its bioactive constituents, it can be exploited in the development of pharmaceutical products and functional foods. However, there is a need for comprehensive studies in clinical trials to establish the safe doses and efficacy of P. guajava for the treatment of several diseases.     

Use of carbon adsorption traps combined with high resolution gas chromatography – mass spectrometry for the analysis of polar and non-polar C4-C14 hydrocarbons involved in photochemical smog formation

A method has been developed for the collection and analysis of polar and non-polar C₄-C₁₄ hydrocarbons involved in the formation of photochemical smog. Enrichment of hydrocarbons from both polluted and unpolluted areas has been achieved with three-stage traps packed with carbon adsorbents of different surface area; the use of a home-made desorption unit employing cryofocusing then enables the determination of the compounds by HRGC-FID. Two-stage traps filled with graphitic carbon have been used prior to GC-MS identification and quantitation of compounds producing overlapping peaks. The methodology has been tested in the urban area of Rome and in a pine forest, and more than 140 different compounds identified and quantitated. Many of the constituents were found to be oxygenated, either formed by photochemical reactions or of anthropogenic origin.