Gamma mixture models for target recognition

This paper considers a mixture model approach to automatic target recognition using high-resolution radar measurements. The mixture model approach is motivated from several perspectives including requirements that the target classifier is robust to uncertainty in amplitude scaling, rotation and translation of the target. Estimation of the model parameters is achieved using the expectation-maximisation (EM) algorithm. Gamma mixtures are introduced and the re-estimation equations derived. The models are applied to the classification of high-resolution radar range profiles of ships and results compared with a previously published self-organising map approach.     

Limiting optimal discounted-cost control of a class of time-varying stochastic systems

We consider a class of time-varying -valued control models, and with possibly unbounded costs. The processes evolve according to the system equation x_n+1=G_n(x_n,a_n)+ξ_n ( ), where {ξ_n} are i.i.d. random vectors and {G_n} a sequence of known functions converging to some function G_∞. Under suitable hypotheses, we show the existence of an α-discount optimal policy for the limiting system x_n+1=G_∞(x_n,a_n)+ξ_n.     

主动网络安全研究

由于当前Ｉｎｔｅｒｎｅｔ是不可编程的,难以提供各种新的网络服务,并且新协议配置困难,因此提出了主动网络模型来解决当前基于ＩＰ模型的各种问题,但在提供灵活性的同时也产生了更多的安全问题。该文分析了各种安全隐患,并探讨了对主动网络体系结构的安全问题的不同解决办法。     

正规网格等值线的虚路径扫描算法

等值线图在工程分析和计算领域有着广泛的应用。该文以正规化的采样数据为研究对象,提出了一种全新的虚路径扫描算法。算法在数据网格基础之上构筑一虚拟的路径网格,利用路径网格上的线段（虚路径）来记录等值点的追踪路径信息。所有等值线的虚路径的捕获只需通过一次性扫描即可完成,不仅提高了追踪效率,而且避免了以往等值线追踪算法初始点选择困难、网格出口边判断复杂等一系列问题。算法的另一优点是追踪结果的精度是可控的,取决于等值点如何取值。该算法在土地定级中的作用分等值线图绘制中得到很好的应用。虚路径的思想同样适用于非正规的采样数据。     

Web网站维护的一种方法

提出一种较新颖的Web网站维护方法,介绍了其设计思想、相关技术、实现方法与应用实例。     

Simulation of Foreign Trade Activity under Transition Economy Conditions

A system of mathematical models of foreign economic activity under transition economy conditions is considered. Input-output optimization models and econometric micromodels are the basis of this system. Simulation using real data and the mentioned models is performed. The obtained results allow us to explain some features of the structure of the Ukrainian export.     

Multi-Modal Dialog Scene Detection Using Hidden Markov Models for Content-Based Multimedia Indexing

A class of audio-visual data (fiction entertainment: movies, TV series) is segmented into scenes, which contain dialogs, using a novel hidden Markov model-based (HMM) method. Each shot is classified using both audio track (via classification of speech, silence and music) and visual content (face and location information). The result of this shot-based classification is an audio-visual token to be used by the HMM state diagram to achieve scene analysis. After simulations with circular and left-to-right HMM topologies, it is observed that both are performing very good with multi-modal inputs. Moreover, for circular topology, the comparisons between different training and observation sets show that audio and face information together gives the most consistent results among different observation sets.     

Managing Workflow Authorization Constraints through Active Database Technology

The execution of workflow processes requires authorizations for enforcing the assignment of tasks to agents, either human or automated, according to the security policy of the organization. This paper presents a workflow authorization framework based on roles and organizational levels, and on authorization constraints. To facilitate the assignment of tasks to agents, roles and organizational levels are organized into hierarchies. Authorization constraints are introduced to specify instance-dependent, time-dependent, and history-dependent authorizations. Authorization constraints are specified in terms of active rules, used also for authorization management. The Workflow Management System determines authorized agents on the basis of the contents of an authorization base maintained through the active rules defined in the system.