谓词μ演算和模态图的语义一致性

模态图是谓词μ演算的一种有效的图形表示形式。证明了谓词μ演算和模态图的语义一致性，详细讨论了谓词μ演算公式、嵌套谓词等式系和模态图之间的关系，并给出了一种优化的从线性公式到嵌套谓词等式系的转换算法。

带赋值符号迁移图的局部优化算法

National Natural Science Foundation of China; Public Administration and Civil Service Bureau of Macau SAR; Companhia de Telecomunicacoes de Macau S.A.R.L.; Macau SAR Government Tourist Office

一种基于OBDD图的事件复合匹配方法

基于内容的Pub／Sub系统的核心问题是基于内容的事件匹配．在现有的方法中，订阅者使用简单约束来匹配事件内容，难以支持事件复合匹配．针对此问题，提出新的匹配模型，扩展简单匹配方法为多语义匹配并引入时间约束变量，支持依据语义对事件采取不同的操作和离散事件的处理，增强了事件匹配表达能力.在此基础上，将OBDD图扩展为层次着色OBDD图，证明了图扩展的等价性，给出基于扩展ODBB图的复合匹配算法，分析并验证了该算法的有效性．

Determination of appropriate condition on replacing methane from hydrate with carbon dioxide

This paper is intended to determine the appropriate conditions for replacing CH4 from NGH with CO2. By analyzing the hydration equilibrium graphs and geotherms, the HSZs of NGH and CO2 hydrate, both in permafrost and under deep sea, were determined. Based on the above analysis and experimental results, it is found that to replace CH4 from NGH with gaseous CO2, the appropriate experimental condition should be in the area surrounded by four curves: the geotherm, (H-V)(CO2), (L-V)(CO2) and (H-V)(CH4), and to replace CH4 from NGH with liquid CO2, the condition should be in the area surrounded by three curves: (L-V)(CO2), (H-L)(CO2) and (H-V)CH4. For conditions in other areas, either CO2 can not form a hydrate or CH4 can release little from its hydrate, which are not desirable results.

基于GIS和CSLE的陕西省土壤侵蚀定量评价方法研究

通过对陕西省土壤侵蚀的定量评估,探索省域尺度上土壤侵蚀定量评价制图方法,以期为第四次全国土壤侵蚀普查提供技术支撑。利用陕西省日降雨数据、土壤类型图、土地利用图、DEM、植被覆盖图,选择CSLE模型,在ArcGIS平台上计算研究区2006年土壤侵蚀量,并与水利部标准评价结果进行对比分析。探索了坡度坡长变换对土壤侵蚀的影响。定量化的评价结果能较好的反映气候、土壤及水保措施对土壤侵蚀的影响,比水利部标准评价结果更能反映实际侵蚀。坡度坡长变换后对土壤侵蚀有明显影响。在GIS支持下,通过土壤侵蚀模型进行定量评价,可高效、客观反映土壤侵蚀情况及其主要影响因子,对区域治理和有关决策有极其重要参考价值。为了准确真实的反映土壤侵蚀程度,必须进行坡度坡长变换。

Magnetic characterization of Co1-xNixFe2O4 (0 <= x <= 1) nanoparticles prepared by co-precipitation route

Magnetic nanoparticles of Ni-doped cobalt ferrite [Co1-xNixFe2O4(0 <= x <= 1)] synthesized by coprecipitation route have been studied as a function of doping concentration (x) and particle size. The size of the particles as determined by X-ray diffractometer (XRD) and transmission electron microscope (TEM) analyses was found in the range 12-48 nm. The coercivity (H-C) and saturation magnetization (M-S) showed a decreasing behavior with increasing Ni concentration. M-S of all the samples annealed at 600 degrees C lies in the range 65.8-13.7 emu/gm. Field-cooled (FC) studies of the samples showed horizontal shift (exchange bias) and vertical shift in the magnetization loop. Strong decrease in exchange bias (H-b) and vertical shift (delta M) was found for low Ni concentrations while negligible decrease was found at higher concentrations. The presence of exchange bias in the low Ni-concentration region has been explained with reference to the interface spins interaction between a surface region (with structural and spin disorder) and a ferrimagnetic core region. M(T) graphs of the samples showed a decreasing trend of blocking temperature (T-b) with increasing Ni concentration. The decrease of T-b with increasing Ni concentration has been attributed to the lower anisotropy energy of Ni+2 ions as compared to Co+2 that increases the probability of the jump across the anisotropy barrier which in turn decreases the blocking temperature of the system.

Range-based attacks on links in random scale-free networks

Range and load play key roles in the problem of attacks on links in random scale-free (RSF) networks. In this paper we obtain the approximate relation between range and load in RSF networks by the generating function theory, and then give an estimation about the impact of attacks on the efficiency of the network. The results show that short-range attacks are more destructive for RSF networks, and are confirmed numerically.

Holographic dual of linear dilaton black hole in Einstein-Maxwell-dilaton-axion gravity

Motivated by the recently proposed Kerr/CFT correspondence, we investigate the holographic dual of the extremal and non-extremal rotating linear dilaton black hole in Einstein-Maxwell-Dilaton-Axion Gravity. For the case of extremal black hole, by imposing the appropriate boundary condition at spatial infinity of the near horizon extremal geometry, the Virasoro algebra of conserved charges associated with the asymptotic symmetry group is obtained. It is shown that the microscopic entropy of the dual conformal field given by Cardy formula exactly agrees with Bekenstein-Hawking entropy of extremal black hole. Then, by rewriting the wave equation of massless scalar field with sufficient low energy as the SLL(2, R) x SLR(2, R) Casimir operator, we find the hidden conformal symmetry of the non-extremal linear dilaton black hole, which implies that the non-extremal rotating linear dilaton black hole is holographically dual to a two dimensional conformal field theory with the non-zero left and right temperatures. Furthermore, it is shown that the entropy of non-extremal black hole can be reproduced by using Cardy formula.

Entropy of Kaluza-Klein black hole from Kerr/CFT correspondence

We extend the recently proposed Kerr/CFT correspondence to examine the dual conformal field theory of four-dimensional Kaluza-Klein black hole in Einstein-Maxwell-Dilaton theory. For the extremal Kaluza-Klein black hole, the central charge and temperature of the dual conformal field are calculated following the approach of Guica, Hartman, Song and Strominger. Meanwhile, we show that the microscopic entropy given by the Cardy formula agrees with Bekenstein-Hawking entropy of extremal Kaluza-Klein black hole. For the non-extremal case, by studying the near-region wave equation of a neutral massless scalar field, we investigate the hidden conformal symmetry of Kaluza-Klein black hole, and find the left and right temperatures of the dual conformal field theory. Furthermore, we find that the entropy of non-extremal Kaluza-Klein black hole is reproduced by Cardy formula. (C) 2010 Elsevier B.V. All rights reserved.

基于Context_Graphs的主题爬虫系统的设计与实现

为了利用有限的硬件资源和存储空间，即时获取网络上用户最关心的数据，研究者们提出了主题爬虫。以往的通用爬虫既不考虑页面内容与主题的相关度，也不做任何预测，相比之下，主题爬虫以一定策略去评价网页的优先度，选择最为可能获取主题网页的路径进行搜索，因此有能力更快更准地获取目标网页。 主题爬虫爬行策略有很多方法，其中，Context Graphs方法是一种结合了网页的文字内容信息与Web超链结构信息的综合方法。Context Graphs方法将网络中的页面视为分层的结构，链接到达主题网页的页面根据其特征会被分到一定层次中。基于各个层次的特征，可以指导爬行器更快地去发掘可能存在的主题页面。然而，以往的Context Graphs方法在建立层次模型的时候没有区分网页不同部分文本信息的重要程度，但是在很多情况下，网页标题、超链锚文字等信息在区分网页主题时比网页正文内容更重要。此外，Context Graphs方法在指导抓取的时候不能根据新得到的主题网页更新模型，事实上，如果能利用这些新得到的网页来增量更新模型，将有可能获得更为准确的结果。基于这两点，作者提出了一种采用混合打分法以及引入模型反馈更新机制的M-Context Graphs方法，并进一步设计并实现了一个主题爬虫原型系统。 本文首先对目前已有的和正在探索中的各种主题爬行策略进行了综述和分析，并对国内外主题爬虫系统的开发现状做了简要介绍；接下来，本文详细介绍了M-Context Graphs方法中的混合打分法和模型反馈更新策略，并进一步给出了一个主题爬虫原型系统的详细设计和实现方案。最后，利用该系统通过实验比较了M-Context Graphs算法与以往算法，结果表明，M-Context Graphs方法确实获得了更好的效果。

Robustness and Coherence of a Three-Protein Circadian Oscillator: Landscape and Flux Perspectives

Three-protein circadian oscillations in cyanobacteria sustain for weeks. To understand how cellular oscillations function robustly in stochastic fluctuating environments, we used a stochastic model to uncover two natures of circadian oscillation: the potential landscape related to steady-state probability distribution of protein concentrations; and the corresponding flux related to speed of concentration changes which drive the oscillations. The barrier height of escaping from the oscillation attractor on the landscape provides a quantitative measure of the robustness and coherence for oscillations against intrinsic and external fluctuations. The difference between the locations of the zero total driving force and the extremal of the potential provides a possible experimental probe and quantification of the force from curl flux. These results, correlated with experiments, can help in the design of robust oscillatory networks.

Developing molecular identification numbers by an all-paths method

A new topological index is devised from an all-paths method. This molecular topological index has highly discriminating power for various kinds of organic compounds such as alkane trees, complex cyclic or polycyclic graphs, and structures containing heteroatoms and thus can be used as a Molecular IDentification number (MID) for chemical documentation. Some published MIDs derived from an all-paths method and their structural selectivity for alkane trees are also reviewed.