Mirko Randić

Modeling Service Dependencies in Ad Hoc Collaborative Systems

Several service management tasks or activities benefit from - or are even impossible without - the knowledge about service dependencies. Ad hoc collaborative environments impose special problems to the dependency modeling. In this paper we analyze these problems and propose a modeling approach for specifying static and dynamical aspects of dependencies. Modeling is based on the standard Unified Modeling Language, UML. Besides the standard modeling constructs we use new tagged values too. Applicability of the modeling approach is tested on prototypical applications which are developed on top of the Anhinga infrastructure

Advantages of online spellchecking: a Croatian example

Online spellchecking is commonly regarded as an auxiliary way of performing spellchecking. However, it offers a unique opportunity to constantly improve spellchecker linguistic functionality through interaction with the community of spellchecker users. Such a possibility is crucial for spellchecking in non‐central and under‐resourced languages, in order to overcome gaps in NLP tools between them and central languages. The paper describes Hascheck, a Croatian online spellchecker able to learn words from texts it receives. It started as the first Croatian spellchecker, hence as a basic NLP tool for an under‐resourced language, but due to its learning ability it demonstrates linguistic functionality comparable to that of conventional central‐language spellcheckers. Based on these experiences we also discuss the future of online spellchecking in the context of global NLP tasks. Copyright

Agent-based modeling of transmission power system for supervision and control

Restructuring and deregulation of the electric power systems is the key factor that is particularly affecting power system operation. In this new competitive environment it is essential to ensure reliable power system operation, supervision and control of the whole system. Introducing new types of devices, that provide the whole lot more information from the system, creates the problem for the operator who has to manage it. Complexity of the system is increasing and new approaches must be considered to help operators. To overcome this complexity agent-based model and control policy specification are proposed. Proposed model is based on the Common Information Model and object oriented approach.

Information modeling of power substations by using the unified modeling language

Efficient and high-quality design of the substation automation systems has always been a real challenge. The problem of identification and location of information in the system and the description of information processing activities is a significant design problem. Information modeling is aimed at resolving it. An efficient approach to information modeling can significantly improve substation automation system development process. In this paper we propose the usage of the Unified Modeling Language (UML) as a main modeling language for expressing substation information models. UML was specified by Rational Software Corporation in 1997. Today, UML is adopted by the Object Management Group as an object-oriented modeling language with formally defined syntax and semantics. As expected, UML could be widely accepted in various industries (software, telecommunications, medicine, electro-industry, aero-industry etc.). The modeling approach is explained on one typical small-range 35 kV/10 kV distribution substation. Modeling steps: system usage specification, system structure specification, and behavior and constraints specification are described together with explanation of usage of some UML diagrams and modeling concepts.

A Multivariate Approach to Predicting Quantity of Failures in Broadband Networks Based on a Recurrent Neural Network

In this paper, we present a multivariate recurrent neural network model for short-time prediction of the number of failures that are expected to be reported by users of a broadband telecommunication network. An accurate prediction of the expected number of reported failures is becoming increasingly important to service providers. It enables proactive actions and improves the decision-making process, operational network maintenance, and workforce allocation. Our previous studies have shown that the recursive neural network is flexible enough to approximate the dynamics of the failure reporting process. Development of the model is based on long-term monitoring of failure-reporting processes and experience gained through fault management related to the network of one of the leading Croatian telecom providers (T-HT). Many factors, both in the network and outside the network, influence the time series representing failure reporting. The model encompasses the most important predictor variables and their logical and temporal dependencies. Predictor variables represent internal factors such as profiles of past and current quantities of failures as well as external factors like weather forecasts or announced activities (scheduled maintenance) in the network. External factors have a strong effect on fault occurrence, which finally results in failures reported by users. These factors are quantified and included as input variables to our model. The model is fitted to the data from different sources like an error-logging database, a trouble-ticket archive, announced settings logs and a meteo-data archive. The accuracy of the model is examined on simulation tests varying the prediction horizons. Assessment of the model’s accuracy is made by comparing results obtained by prediction and the actual data. This research represents a real-world case study from telecom operations. The developed prediction model is scalable and adaptable so that other relevant input factors can be added as needed. Hence, the proposed prediction approach based on the model can be efficiently implemented as a functionality in real fault-management processes where a variety of available input data of different volumes exist.

From Declarative Model to Solution: Scheduling Scenario Synthesis

This paper presents deductive programming for scheduling scenario generation. Modeling for solution is achieved through program transformations. First, declarative model for scheduling problem domain is introduced. After that model is interpreted as scheduling domain language and as predicate transition Petri net. Generated reachability tree presents search space with solutions. At the end results are discussed and analyzed.

Application design for ad hoc collaboration environment based on dependency injection pattern

In this paper we elaborate applicability of dependency injection pattern as a design solution for ad hoc network applications development. Dependency injection pattern promotes inversion of control. Inversion of control has to put the server to control the binding process. Our main idea was an architecture with a thin client and a server with more competences that promote competition of servers. We suppose that a server is interested to be occupied by servicing as much as possible. It discovers for possible engagements and optionally makes a dependency injection to a client. This is about servers that compete for an engagement, not about clients that find servers. Static and dynamical aspects of the application are specified by the UML. For the system implementation we used the LIME middleware and Java technology

Model checking approach for communication procedures validation

Quality assurance is an important part of communicating systems development. In order to find errors communicating procedures are analysed as early as possible, during the requirements or specification phase. This paper discuss validation of communicating procedures. Special attention is exercised on extraction of the data from real system descriptions through model extraction. Examples are given.

Linear network analyser design with heterogeneous component composition

This paper describes the development of linear network analyser software. The software development is based on coordination between heterogenous software components within (CO)/sup 4/PE metamodelling environment. As solution, the language for component coordination is introduced. Coordination formalism is based on high level Petri nets providing great flexibility and reusability during component composition.

Information modeling of applications using mobile management agents with extensible behavior in run-time

Software agent technology is a new and an emerging technology. It is an active research area today. Generally, a software agent is defined as an autonomous software entity that can interact with its environment. Mobile agents represent a special class of agents capable of transporting itself from one environment or platform to another. Agents of this type can be successfully used to assist in complex telecommunications network and system management tasks such as: operation monitoring, load balancing, rebooting, failure anticipation, problem analysis, etc. Moreover, mobile agents allow one to decrease the pressure on centralized network management systems by delegation of specific management activities from the central operations system to spatially dispersed management agents. The expected benefits represent a motive to better develop applications using agent modeling and is one of the most important phase in such a development. It is concerned with the identification and location of information in the systems and the description of information processing activities, but completely independent of the system implementation. We explain our approach to information modeling of management applications using mobile agents. The approach is based on the usage of two modeling languages: Unified Modeling Language (UML) with adequate extensions as well as the Object Constraint Language (OCL).