浅析古典概型

古典概型是一种概率模型。古典概率讨论的对象局限于随机试验所有可能结果为有限个等可能的情形，基本空间由有限个元素或基本事件组成，其个数记为N，每个基本事件发生的可能性是相同的。若事件A包含n个基本事件，则定义事件A发生的概率为P（A）=nN，也就是事件A发生的概率等于事件A所包含的基本事件个数除以基本空间的基本事件的总个数。

Research of NS dataflow mechanism and its analyzer implementation

This paper analyzes the main elements in NS network simulator, makes adetailed view of dataflow management in a link, a node, and an agent, respectively, and introducesthe information described by its trace file. Based on the analysis of transportation and treatmentof different packets in NS, a dataflow state machine is proposed with its states exchange triggeringevents and a dataflow analyzer is designed and implemented according to it. As the machine statefunctions, the analyzer can make statistic of total transportation flux of a specified dataflow andoffer a general fluctuation diagram. Finally, a concrete example is used to test its performance.

Analysis on the semantic relationships in event structures on the basis of ontology

Ontology is a distinct, canonical and shared system of concepts, which is oriented to objects （fields）. Nowadays, every discipline or field attaches great importance to establishing and applying ontology for research. And ontologies that related to linguistics are WordNet by cognitive linguist Prof. Miller from PrincetonUniversity, FrameNet by Prof. Fillmore from California University, Berkeley, GOLD （General Ontology for Language Description） by Dr. Farrar from Arizona University and DOLCE （Descriptive Ontology for Linguistic and Cognitive Engineering） by CNR cognitive science and technology research centre of Italy, etc. This article focuses on event structures hot discussed in cognitive linguistics, through an ontologically analytical approach, and gives a systematic description on the concepts and semantic relationships involved in the event structures. Any event structure can be represented through the 7S schema. ＂For some purpose, somebody does something for someone with some means, sometimes and somewhere＂. Therefore, an event consists of 7 conceptual domains： purpose, actor, action, object, facility, location and time. In the article, the main concepts of the 7 domains and over 20 semantic relationships between these domains are described in detail and illustrated by some examples.

Facts and Fiction. Events and Stories in Relation to Texts and the World

This paper, as a part of a larger research project entitled Amazon. Realities in the Novels and the Imaginary Reports of Travelers, focuses on the following objectives： （1） the ＂referentiality＂ of the text to the external world （goal, empirical stuff）; and （2） understanding fictionality in terms of＂make-believe＂ and the principle of＂internal coherence＂. The main section sets out the theoretical foundation of the relation between facts/events and fiction, both as pragmatic and fictional texts. Then, the paper investigates in which forms and ways existing facts, data, occurrences, events and narratives in various kinds of texts constitute a representation and interpretation of the world. The central focus of the study is on the Amazon region. The study is an experiment in joining together different types of texts around the notion of＂referentiality＂; emphasizing reference to the external world （factuality）, the reading of the component elements of a language and a discourse （narratology）, historical reading against the horizon of expectation （reception theory） and the interpretation of the retrospective.

Handling epistemic uncertainties in PRA using evidential networks

In order to overcome the limitations of traditional methods in uncertainty analysis, a modified Bayesian network(BN), which is called evidence network(EN), was proposed with evidence theory to handle epistemic uncertainty in probabilistic risk assessment(PRA). Fault trees(FTs) and event trees(ETs) were transformed into an EN which is used as a uniform framework to represent accident scenarios. Epistemic uncertainties of basic events in PRA were presented in evidence theory form and propagated through the network. A case study of a highway tunnel risk analysis was discussed to demonstrate the proposed approach. Frequencies of end states are obtained and expressed by belief and plausibility measures. The proposed approach addresses the uncertainties in experts' knowledge and can be easily applied to uncertainty analysis of FTs/ETs that have dependent events.

Optimal Precursor Perturbations of El Ni?o in the Zebiak-Cane Model for Different Cost Functions

Optimal precursor perturbations of El Nino in the Zebiak-Cane model were explored for three different cost functions. For the different characteristics of the eastern-Pacific （EP） El Nino and the central-Pacific （CP） El Nino, three cost functions were defined as the sea surface temperature anomaly （SSTA） evolutions at prediction time in the whole tropical Pacific, the Nino3 area, and the Nino4 area. For all three cost functions, there were two optimal precursors that developed into El Nino events, called Precursor Ⅰ and Precursor Ⅱ. For Precursor Ⅰ, the SSTA component consisted of an east-west （positive-negative） dipole spanning the entire tropical Pacific basin and the thermocline depth anomaly pattern exhibited a tendency of deepening for the whole of the equatorial Pacific. Precursor Ⅰ can develop into an EP-El Nino event, with the warmest SSTA occurring in the eastern tropical Pacific or into a mixed El Nino event that has features between EP-El Nino and CP-El Nino events. For Precursor Ⅱ, the thermocline deepened anomalously in the eastern equatorial Pacific and the amplitude of deepening was obviously larger than that of shoaling in the central and western equatorial Pacific. Precursor Ⅱ developed into a mixed El Nino event. Both the thermocline depth and wind anomaly played important roles in the development of Precursor Ⅰ and Precursor Ⅱ.

Analysis of Pseudomomentum Wave-Activity Density in a Heavy Rainfall Event in East China

Taking into account moisture in virtue of general potential temperature,the author derive a three-dimensional(3D) pseudomomentum wave-activity relation for the moist atmosphere from the primitive equations in Cartesian coordinates using the Momentum-Casimir method.Since the wave-activity relation is constructed in an ageostrophic and non-hydrostatic dynamical framework,it may be applicable to diagnosing the evolution and propagation of mesoscale systems leading to heavy rainfall.The theoretical analysis shows that,besides the local change of wave-activity flux divergence and source or sink,the wave-activity relation includes two additional forcing terms.The first is the zonal gradient of difference between general potential temperature and potential temperature perturbations,and the second is the covariance of the solenoid and gradient of water vapor,denoting the direct influence of moisture on wave-activity density.The wave-activity density was applied to a heavy precipitation event occurring in the Jianghuai region of China.The calculation showed that the wave-activity density was consistent with 6-h accumulated precipitation observations,in terms of both spatial distribution and temporal tendency.This suggested that the disturbance represented by wave-activity density was closely related to the heavy precipitation.Although the wave-activity flux divergence and the covariance of the solenoid and gradient of water vapor made the primary contribution to the local change of wave-activity density,the covariance was more remarkable.The zonal gradient of difference between general potential temperature and potential temperature perturbations made a weaker contribution to the waveactivity density.

Suppression dampens unpleasant emotion faster than reappraisal:Neural dynamics in a Chinese sample

The timing dynamics of regulating negative emotion with expressive suppression and cognitive reappraisal were investigated in a Chinese sample. Event-Related Potentials were recorded while subjects were required to view, suppress emotion expression to, or reappraise emotional pictures. The results showed a similar reduction in self-reported negative emotion during both strategies. Additionally, expressive suppression elicited larger amplitudes than reappraisal in central-frontal P3 component(340–480 ms). More importantly, the Late Positive Potential(LPP) amplitudes were decreased in each 200 ms of the 800–1600 ms time intervals during suppression vs. viewing conditions. In contrast, LPP amplitudes were similar for reappraisal and viewing conditions in all the time windows, except for the decreased amplitudes during reappraisal in the 1400–1600 ms. The LPP(but not P3) amplitudes were positively related to negative mood ratings, whereas the amplitudes of P3, rather than LPP, predict self-reported expressive suppression. These results suggest that expressive suppression decreases emotion responding more rapidly than reappraisal, at the cost of greater cognitive resource involvements in Chinese individuals.

Unusual Event Detection and Prediction in Real-life Scenes

In this paper,we consider unusual event detection problem in a novel viewpoint and provide an algorithm to solve the problem.The actions or events in the scene is usual or not will eventually be reflected on the changes of some basic features.We summarize these basic event features and propose special representation for each of them.Thus we can model these features in a uniform mode using adaptive Gaussian mixture model.Supervised and unsupervised unusual event detection algorithm can be designed to fit various situations based on this model.The superiority of our model is that it can detect unusual event automatically without to know the determinate model of unusual events.In conclusion,we provide two applications to verify the effectiveness of our model.