文本会话抽取将网络聊天记录等短文本信息流中的信息根据其所属的会话分检到多个会话队列,有利于短文本信息的管理及进一步的挖掘.现有的会话抽取技术主要对基于文本相似度的聚类方法进行改进,面临着短文本信息流的特征稀疏性、奇异性...文本会话抽取将网络聊天记录等短文本信息流中的信息根据其所属的会话分检到多个会话队列,有利于短文本信息的管理及进一步的挖掘.现有的会话抽取技术主要对基于文本相似度的聚类方法进行改进,面临着短文本信息流的特征稀疏性、奇异性和动态性等挑战.针对这些挑战,研究无监督的会话抽取技术,提出了一种基于信息流时序特征和上下文相关度的抽取方法.首先研究了信息流的会话生命周期规律,提出基于信息产生频率的会话边界检测方法;其次提出信息间的上下文相关度概念,采用基于实例的机器学习方法计算该相关度;最后综合信息产生频率和上下文相关度,设计了基于Single-Pass聚类模型的会话在线抽取算法SPFC(single-pass based on frequency and correlation).真实数据集上的实验结果表明,SPFC算法与已有的基于文本相似度的会话抽取算法相比,F1评测指标提高了30%.展开更多
In this paper, a numerical modeling tool is described which can be used to explore various aspects of four dimensional variational data assimilation and parameter estimation arising in geophysical, environmental, biol...In this paper, a numerical modeling tool is described which can be used to explore various aspects of four dimensional variational data assimilation and parameter estimation arising in geophysical, environmental, biological and engineering sciences. A major component of this tool is a coupled chaotic dynamical system obtained by coupling two versions of the well-known Lorenz （1963） model with different time scales which differ by a certain time-scale factor. A tangent linear model and its adjoint are considered that correspond to a coupled chaotic system. The general idea of applying sensitivity measures （sensitivity functions） to coupled systems, emphasizing the data assimilation aspects, is explored as well by the forward sensitivity approach. For this purpose the set of sensitivity equations is derived from the nonlinear equations of the coupled dynamical system. To estimate the influence of model parameter uncertainties on the simulated state variables the relative error in the energy norm is used.展开更多
Harmonization of tax policy at European level is the result of compromise that must be achieved between member states＇ sovereignty and obstacles that create differences in legal regime for different categories of tax...Harmonization of tax policy at European level is the result of compromise that must be achieved between member states＇ sovereignty and obstacles that create differences in legal regime for different categories of taxes. The current level of harmonization achieved by the member states clearly shows that the process of reconciliation of taxes will not be a spontaneous, nor will evolve rapidly. With the occasion of European Union [EU] enlargement in 2004 and 2007, disparities in income levels matter between nationals of member states have put more pressure on the cooperation between member states, but some progress has been made including in this area. The idea of harmonization of taxes in the European plan is not new. Context of pertinent and uniform EU position has occurred since the first treaties concluded between member states. The free movements of goods, persons, services and capital, without any obstruction became absolute values. Creating a European tax, set and charged uniformly to all and by all member states, would be possible only if the criteria of budgetary requirements, criteria of efficiency and equity criteria are taken into consideration. Ruling a uniform level of charging would lead to establishing a single tax, mission almost impossible as long as the legal framework on taxation and civil duties remains under the responsibility of each member of EU. This analysis seems to greatly restrict the area of taxes that may meet all requirements listed. EU is still far from time to harmonize VAT （value added tax） levels perceived, but it is noted that the value added tax, income tax and tax on benefits eventually could meet the characteristics of a uniform European tax, achieving unanimous agreement among member states.展开更多
文摘文本会话抽取将网络聊天记录等短文本信息流中的信息根据其所属的会话分检到多个会话队列,有利于短文本信息的管理及进一步的挖掘.现有的会话抽取技术主要对基于文本相似度的聚类方法进行改进,面临着短文本信息流的特征稀疏性、奇异性和动态性等挑战.针对这些挑战,研究无监督的会话抽取技术,提出了一种基于信息流时序特征和上下文相关度的抽取方法.首先研究了信息流的会话生命周期规律,提出基于信息产生频率的会话边界检测方法;其次提出信息间的上下文相关度概念,采用基于实例的机器学习方法计算该相关度;最后综合信息产生频率和上下文相关度,设计了基于Single-Pass聚类模型的会话在线抽取算法SPFC(single-pass based on frequency and correlation).真实数据集上的实验结果表明,SPFC算法与已有的基于文本相似度的会话抽取算法相比,F1评测指标提高了30%.
文摘In this paper, a numerical modeling tool is described which can be used to explore various aspects of four dimensional variational data assimilation and parameter estimation arising in geophysical, environmental, biological and engineering sciences. A major component of this tool is a coupled chaotic dynamical system obtained by coupling two versions of the well-known Lorenz （1963） model with different time scales which differ by a certain time-scale factor. A tangent linear model and its adjoint are considered that correspond to a coupled chaotic system. The general idea of applying sensitivity measures （sensitivity functions） to coupled systems, emphasizing the data assimilation aspects, is explored as well by the forward sensitivity approach. For this purpose the set of sensitivity equations is derived from the nonlinear equations of the coupled dynamical system. To estimate the influence of model parameter uncertainties on the simulated state variables the relative error in the energy norm is used.
文摘Harmonization of tax policy at European level is the result of compromise that must be achieved between member states＇ sovereignty and obstacles that create differences in legal regime for different categories of taxes. The current level of harmonization achieved by the member states clearly shows that the process of reconciliation of taxes will not be a spontaneous, nor will evolve rapidly. With the occasion of European Union [EU] enlargement in 2004 and 2007, disparities in income levels matter between nationals of member states have put more pressure on the cooperation between member states, but some progress has been made including in this area. The idea of harmonization of taxes in the European plan is not new. Context of pertinent and uniform EU position has occurred since the first treaties concluded between member states. The free movements of goods, persons, services and capital, without any obstruction became absolute values. Creating a European tax, set and charged uniformly to all and by all member states, would be possible only if the criteria of budgetary requirements, criteria of efficiency and equity criteria are taken into consideration. Ruling a uniform level of charging would lead to establishing a single tax, mission almost impossible as long as the legal framework on taxation and civil duties remains under the responsibility of each member of EU. This analysis seems to greatly restrict the area of taxes that may meet all requirements listed. EU is still far from time to harmonize VAT （value added tax） levels perceived, but it is noted that the value added tax, income tax and tax on benefits eventually could meet the characteristics of a uniform European tax, achieving unanimous agreement among member states.
