Método para análise da interação fluido-estrutura em travessas do pré-distribuidor de turbinas hidráulicas.

Um dos grandes desafios enfrentados pelos fabricantes de turbinas hidráulicas é prevenir o aparecimento de vibrações induzidas pelo escoamento nas travessas do pré-distribuidor e pás do rotor. Considerando apenas as travessas, e atribuídos a tais vibrações, foram relatados 28 casos de trincas ou ruídos anormais nas últimas décadas, que acarretaram enormes prejuízos associados a reparos, atrasos e perda de geração. O estado da arte na prevenção destes problemas baseia-se na utilização de sofisticados, e caros, programas comerciais de dinâmica dos fluidos computacional para o cálculo transiente do fenômeno. Este trabalho faz uma ampla revisão bibliográfica e levantamento de eventos de trincas ou ruídos ocorridos em travessas nos últimos 50 anos. Propõe, então, um enfoque alternativo, baseado exclusivamente em ferramentas de código aberto. A partir de hipóteses simplificadoras devidamente justificadas, o problema é formulado matematicamente de forma bidimensional, no plano da seção transversal da travessa, levando em conta a interação fluido-estrutura. Nesta estratégia, as equações de Navier-Stokes são resolvidas pelo método dos elementos finitos por meio da biblioteca gratuita oomph-lib. Um código especial em C++ é desenvolvido para o problema de interação fluido-estrutura, no qual o fenômeno de turbulência é levado em consideração por meio de um algoritmo baseado no modelo de Baldwin-Lomax. O método proposto é validado por meio da comparação dos resultados obtidos com referências e medições disponíveis na literatura, que tratam de problemas de barras retangulares suportadas elasticamente. O trabalho finaliza com a aplicação do método a um estudo de caso envolvendo uma travessa particular.

Personalización de aplicaciones en OO-H

Comunicación presentada en las V Jornadas Iberoamericanas de Ingeniería de Requisitos y Ambientes Software (IDEAS’02), La Habana, Cuba, abril 2002.

Modelado conceptual de aplicaciones adaptivas y proactivas en OO-H

Comunicación presentada en las VII Jornadas de Ingeniería del Software y Bases de Datos (JISBD 2002), dentro del II Taller sobre Ingeniería del Software Orientada al Web (Web Engineering) WebE'2002, El Escorial, Madrid, 19 noviembre 2002.

Modelado de estrategias de personalización en OO-H

The consideration of personalization politics in the context of any web application modelling method obliges to the revision of its different modelling activities, which must be adapted to take into account the information regarding the user (usually gathered in a user model) to define aspects such as navigation or presentation. Additionally, they must provide a set of techniques to populate such user model. Finally, and because of the rapid pace at which personalization politics usually change, the modelling process should provide support not only for static personalization rules (known at design time) but also for the definition or change of these rules once the application has been deployed. This article presents, in the context of the Object Oriented Hypermedia Method (OO-H), a personalization framework that fulfils these requirements, and is organized around four main concepts: (1) a set of design activities that capture the personalization requirements known at design time, (2) a mechanism for the specification of personalization rules, defined by means of an XML template, that decouples the definition of the personalization model from the remaining models, (3) an execution architecture that supports the change at execution time of these rules and (4) an extensible repository that includes a set of register mechanisms for the user activity in the system. The possibility of extension of this repository facilitates its adaptation to the particular characteristics of any particular application.

Optimization of the Modular Educational Program Structure

Optimized structure of the educational program consisting of a set of the interconnected educational objects is offered by means of problem solution of optimum partition of the acyclic weighed graph. The condition of acyclicity preservation for subgraphs is formulated and the quantitative assessment of decision options is executed. The original algorithm of search of quasioptimum partition using the genetic algorithm scheme with coding chromosomes by permutation is offered. Object-oriented realization of algorithm in language C++ is described and results of numerical experiments are presented.

Spatial distribution and morphometric analysis of thermokarst lakes and other water bodies : Case study from the sporadic permafrost region, Tavvavuoma, Sweden

Projected air and ground temperatures are expected to be higher in Arctic and sub-Arcticlatitudes and with temperatures already close to the limit where permafrost can exist,resistance against degradation is low. With thawing permafrost, the landscape is modifiedwith depression in which thermokarst lakes emerge. In permafrost soils a considerableamount of soil organic carbon is stored, with the potential of altering climate even furtherif expansion and formation of new thermokarst lakes emerge, as decay releasesgreenhouse gases (C02 and CH4) to the atmosphere. Analyzing the spatial distribution andmorphometry over time of thermokarst lakes and other water bodies, is of importance inaccurately predict carbon budget and feedback mechanisms, as well as to assess futurelandscape layout and these features interaction. Different types of high-spatial resolutionaerial and satellite imageries from 1963, 1975, 2003, 2010 and 2015, were used in bothpre- and post-classification change detection analyses. Using object oriented segmentationin eCognition combined with manual adjustments, resulted in digitalized water bodies>28m2 from which direction of change and morphometric values were extracted. Thequantity of thermokarst lakes and other water bodies was in 1963 n=92, with succeedingyears as a trend decreased in numbers, until 2010-2015 when eleven water bodies wereadded in 2015 (n=74 to n=85). In 1963-2003, area of these water bodies decreased with50 651m2 (189 446-138 795m2) and continued to decrease in 2003-2015 ending at 129337m2. Limnicity decreased from 19.9% in 1963 to 14.6% in 2003 (-5.3%). In 2010 and2015 13.7-13.6%. The late increase in water bodies differs from an earlier hypothesis thatsporadic permafrost regions experience decrease in both area and quantity of thermokarstlakes and water bodies. During 1963-2015, land gain has been in dominance of the ratiobetween the two competing processes of expansion and drainage. In 1963-1975, 55/45%,followed by 90/10% in 1975-2003. After major drainage events, land loss increased to62/38% in 2010-2015. Drainage and infilling rates, calculated for 15 shorelines werevaried across both landscape and parts of shorelines, with in average 0.17/0.15/0.14m/yr.Except for 1963-1975 when rate of change in average was in opposite direction (-0.09m/yr.), likely due to evident expansion of a large thermokarst lake. Using a squaregrid, distribution of water bodies was determined, with an indistinct cluster located in NEand central parts. Especially for water bodies <250m2, which is the dominant area classthroughout 1963-2015 ranging from n=39-51. With a heterogeneous composition of bothsmall and large thermokarst lakes, and with both expansion and drainage altering thelandscape in Tavvavuoma, both positive and negative climate feedback mechanisms are inplay - given that sporadic permafrost still exist.

Ontological evaluation of enterprise systems interoperability using ebXML

Enterprise systems interoperability (ESI) is an important topic for business currently. This situation is evidenced, at least in part, by the number and extent of potential candidate protocols for such process interoperation, viz., ebXML, BPML, BPEL, and WSCI. Wide-ranging support for each of these candidate standards already exists. However, despite broad acceptance, a sound theoretical evaluation of these approaches has not yet been provided. We use the Bunge-Wand-Weber (BWW) models, in particular, the representation model, to provide the basis for such a theoretical evaluation. We, and other researchers, have shown the usefulness of the representation model for analyzing, evaluating, and engineering techniques in the areas of traditional and structured systems analysis, object-oriented modeling, and process modeling. In this work, we address the question, what are the potential semantic weaknesses of using ebXML alone for process interoperation between enterprise systems? We find that users will lack important implementation information because of representational deficiencies; due to ontological redundancy, the complexity of the specification is unnecessarily increased; and, users of the specification will have to bring in extra-model knowledge to understand constructs in the specification due to instances of ontological excess.

Introducing reference semantics via refinement

Two types of semantics have been given to object-oriented formal specification languages. Value semantics denote a class by a set of values representing its objects. Reference semantics denote a class by a set of references, or pointers, to values representing its objects. While adopting the former facilitates formal reasoning, adopting the latter facilitates transformation to object-oriented code. In this paper, we propose a combined approach using value semantics for abstract specification and reasoning, and then refining to a reference semantics before transforming specification to code.

MQL: A powerful extension to OCL for MOF queries

The Meta-Object Facility (MOF) provides a standardized framework for object-oriented models. An instance of a MOF model contains objects and links whose interfaces are entirely derived from that model. Information contained in these objects can be accessed directly, however, in order to realize the Model-Driven Architecture@trade; (MDA), we must have a mechanism for representing and evaluating structured queries on these instances. The MOF Query Language (MQL) is a language that extends the UML's Object Constraint Language (OCL) to provide more expressive power, such as higher-order queries, parametric polymorphism and argument polymorphism. Not only do these features allow more powerful queries, but they also encourage a greater degree of modularization and re-use, resulting in faster prototyping and facilitating automated integrity analysis. This paper presents an overview of the motivations for developing MQL and also discusses its abstract syntax, presented as a MOF model, and its semantics

Defining the Fluid framework

In this position paper we present the developing Fluid framework, which we believe offers considerable advantages in maintaining software stability in dynamic or evolving application settings. The Fluid framework facilitates the development of component software via the selection, composition and configuration of components. Fluid's composition language incorporates a high-level type system supporting object-oriented principles such as type description, type inheritance, and type instantiation. Object-oriented relationships are represented via the dynamic composition of component instances. This representation allows the software structure, as specified by type and instance descriptions, to change dynamically at runtime as existing types are modified and new types and instances are introduced. We therefore move from static software structure descriptions to more dynamic representations, while maintaining the expressiveness of object-oriented semantics. We show how the Fluid framework relates to existing, largely component based, software frameworks and conclude with suggestions for future enhancements. © 2007 IEEE.

A methodology for analysis and control of discrete event dynamic systems

The rapid developments in computer technology have resulted in a widespread use of discrete event dynamic systems (DEDSs). This type of system is complex because it exhibits properties such as concurrency, conflict and non-determinism. It is therefore important to model and analyse such systems before implementation to ensure safe, deadlock free and optimal operation. This thesis investigates current modelling techniques and describes Petri net theory in more detail. It reviews top down, bottom up and hybrid Petri net synthesis techniques that are used to model large systems and introduces on object oriented methodology to enable modelling of larger and more complex systems. Designs obtained by this methodology are modular, easy to understand and allow re-use of designs. Control is the next logical step in the design process. This thesis reviews recent developments in control DEDSs and investigates the use of Petri nets in the design of supervisory controllers. The scheduling of exclusive use of resources is investigated and an efficient Petri net based scheduling algorithm is designed and a re-configurable controller is proposed. To enable the analysis and control of large and complex DEDSs, an object oriented C++ software tool kit was developed and used to implement a Petri net analysis tool, Petri net scheduling and control algorithms. Finally, the methodology was applied to two industrial DEDSs: a prototype can sorting machine developed by Eurotherm Controls Ltd., and a semiconductor testing plant belonging to SGS Thomson Microelectronics Ltd.

A longitudinal study of the diffusion of the ISO/IEC information resource dictionary system standard (IRDS.)

The IRDS standard is an international standard produced by the International Organisation for Standardisation (ISO). In this work the process for producing standards in formal standards organisations, for example the ISO, and in more informal bodies, for example the Object Management Group (OMG), is examined. This thesis examines previous models and classifications of standards. The previous models and classifications are then combined to produce a new classification. The IRDS standard is then placed in a class in the new model as a reference anticipatory standard. Anticipatory standards are standards which are developed ahead of the technology in order to attempt to guide the market. The diffusion of the IRDS is traced over a period of eleven years. The economic conditions which affect the diffusion of standards are examined, particularly the economic conditions which prevail in compatibility markets such as the IT and ICT markets. Additionally the consequences of the introduction of gateway or converter devices into a market where a standard has not yet been established is examined. The IRDS standard did not have an installed base and this hindered its diffusion. The thesis concludes that the IRDS standard was overtaken by new developments such as object oriented technologies and middleware. This was partly because of the slow development process of developing standards in traditional organisations which operate on a consensus basis and partly because the IRDS standard did not have an installed base. Also the rise and proliferation of middleware products resulted in exchange mechanisms becoming dominant rather than repository solutions. The research method used in this work is a longitudinal study of the development and diffusion of the ISO/EEC IRDS standard. The research is regarded as a single case study and follows the interpretative epistemological point of view.

An investigation into the use of knowledge representation in computer-integrated manufacturing

In a certain automobile factory, batch-painting of the body types in colours is controlled by an allocation system. This tries to balance production with orders, whilst making optimally-sized batches of colours. Sequences of cars entering painting cannot be optimised for easy selection of colour and batch size. `Over-production' is not allowed, in order to reduce buffer stocks of unsold vehicles. Paint quality is degraded by random effects. This thesis describes a toolkit which supports IKBS in an object-centred formalism. The intended domain of use for the toolkit is flexible manufacturing. A sizeable application program was developed, using the toolkit, to test the validity of the IKBS approach in solving the real manufacturing problem above, for which an existing conventional program was already being used. A detailed statistical analysis of the operating circumstances of the program was made to evaluate the likely need for the more flexible type of program for which the toolkit was intended. The IKBS program captures the many disparate and conflicting constraints in the scheduling knowledge and emulates the behaviour of the program installed in the factory. In the factory system, many possible, newly-discovered, heuristics would be awkward to represent and it would be impossible to make many new extensions. The representation scheme is capable of admitting changes to the knowledge, relying on the inherent encapsulating properties of object-centres programming to protect and isolate data. The object-centred scheme is supported by an enhancement of the `C' programming language and runs under BSD 4.2 UNIX. The structuring technique, using objects, provides a mechanism for separating control of expression of rule-based knowledge from the knowledge itself and allowing explicit `contexts', within which appropriate expression of knowledge can be done. Facilities are provided for acquisition of knowledge in a consistent manner.

Design and implementation of graphical user interfaces for complex simulations

The development of increasingly powerful computers, which has enabled the use of windowing software, has also opened the way for the computer study, via simulation, of very complex physical systems. In this study, the main issues related to the implementation of interactive simulations of complex systems are identified and discussed. Most existing simulators are closed in the sense that there is no access to the source code and, even if it were available, adaptation to interaction with other systems would require extensive code re-writing. This work aims to increase the flexibility of such software by developing a set of object-oriented simulation classes, which can be extended, by subclassing, at any level, i.e., at the problem domain, presentation or interaction levels. A strategy, which involves the use of an object-oriented framework, concurrent execution of several simulation modules, use of a networked windowing system and the re-use of existing software written in procedural languages, is proposed. A prototype tool which combines these techniques has been implemented and is presented. It allows the on-line definition of the configuration of the physical system and generates the appropriate graphical user interface. Simulation routines have been developed for the chemical recovery cycle of a paper pulp mill. The application, by creation of new classes, of the prototype to the interactive simulation of this physical system is described. Besides providing visual feedback, the resulting graphical user interface greatly simplifies the interaction with this set of simulation modules. This study shows that considerable benefits can be obtained by application of computer science concepts to the engineering domain, by helping domain experts to tailor interactive tools to suit their needs.