The moving boundary method is an appealing approach for the design, testing and validation of advanced control schemes for evaporators and condensers. When it comes to advanced control strategies, not only accurate but fast dynamic models are required. Moving boundary models are fast low-order dynamic models, and they can describe the dynamic behavior with high accuracy. This paper presents a mathematical formulation based on physical principles for two-phase flow moving boundary evaporator and condenser models which support dynamic switching between all possible flow configurations. The models were implemented in a library using the equation-based object-oriented Modelica language. Several integrity tests in steady-state and transient predictions together with stability tests verified the models. Experimental data from a direct steam generation parabolic-trough solar thermal power plant is used to validate and compare the developed moving boundary models against finite volume models. (C) 2014 Elsevier B.V. All rights reserved.

The paper introduces new classes of numerical ODE solvers that base their internal discretization method on state quantization instead of time slicing. These solvers have been coined Quantized State System (QSS) simulators. The main result of this work is a first order accurate QSS-based stiff system solver called Backward QSS (BQSS). The numerical properties of this new algorithm are being discussed, and it is shown that this algorithm exhibits properties that make it a potentially attractive alternative to the classical numerical ODE solvers. Some simulation examples illustrate the advantages of this method. As a colateral result, a first order accurate QSS-based solver designed for solving marginally stable systems is sketched. This new method, called Centered QSS (CQSS), is successfully applied to a new difficult benchmark problem describing a high-order system that is simultaneously stiff and marginally stable

In this paper we introduce new classes of numerical ordinary differential equation (ODE) solvers that base their internal discretization method on state quantization instead of time slicing. These solvers have been coined quantized state system (QSS) simulators. The primary result of the research described in this article is a first-order accurate QSS-based stiff system solver, called the backward QSS (BQSS). The numerical properties of this new algorithm are discussed, and it is shown that this algorithm exhibits properties that make it a potentially attractive alternative to the classical numerical ODE solvers. Some simulation examples illustrate the advantages of this method. As a collateral result, a first-order accurate QSS-based solver designed for solving marginally stable systems is briefly outlined as well. This new method, called the centered QSS (CQSS), is successfully applied to a challenging benchmark problem describing a high-order system that is simultaneously stiff and marginally stable. However, the primary emphasis of this article is on the BQSS method, that is, on a stiff system solver based on state quantization.

This paper describes a fault diagnosis system (FDS) for non-linear plants based on fuzzy logic. The proposed approach, named VisualBlock-FIR, runs under the Simulink framework and enables early fault detection, isolation, and identification. During fault detection, the FDS should recognize that the plant behavior is abnormal, and therefore, that the plant is not working properly. During fault isolation/identification, the FDS should conclude, which type of failure has occurred. The enveloping and acceptability measures introduced in VisualBlock-FIR enhance the robustness of the overall process. The proposed approach is used for tackling faults of the DAMADICS benchmark, and the results are compared with those obtained by other FDS.

Considering the need to reduce waste production and greenhouse emissions by still keeping high energy efficiency, various 4 generation nuclear energy systems have been proposed. As far as graphite moderated reactors are concerned, one of the key issues is the large volumes of irradiated graphite encountered (1770 m for fuel elements and 840 m for reflector elements during the lifetime (60 years) of a single reactor module [1]). With the objective to reduce volume of waste in the HTR concept, it is very important to be able to separate the fuel from low level activity graphite. This requires to separate TRISO particles from the graphite matrix with the sine qua non condition to not break TRISO particles in case of future embedding of particles in a matrix for disposal. According to National Regulatory Systems, in case of limited graphite waste production or of short duration HTR projects (e.g. in Germany), direct disposal without separation is acceptable. Nevertheless, in case of large scale deployment of HTR technology, such approach is not economical and sustainable. Previous attempts in graphite management (furnace, fluidised bed and laser incinerations and encapsulation matrices) dealt with graphite matrix only. These are the reasons why we studied the management of irradiated compact-type fuel element. We simulated the presence of fuel in the particles by using ZrO2 kernels. Compacts with ZrO2 TRISO particles were manufactured by AREVA NP. Two original methods have been studied. First, we tested high pressure jet to erode graphite and clean TRISO particles. Best erosion rate reached about 0.18 kg/h for a single nose ending. Examination of treated graphite showed a mixture of undamaged TRISO particles, particles that have lost the outer pyrolytic carbon layer and ZrO2 kernels. Secondly, we studied the thermal shock method by immerging successively graphite into liquid nitrogen and hot water to cause fracturing of the compact. This produced particles and graphite fragments with diameter ranging from several centimetres to less than 500 μm. This relatively simple and economic method may potentially be considered as a pre-treatment step and be coupled with other method(s) before reprocessing and recycling for example.

Considering the need to reduce waste production and greenhouse emissions by still keeping high energy efficiency, various 4(th) generation nuclear energy systems have been proposed. As far as graphite moderated reactors are concerned, one of the key issues is the large volumes of irradiated graphite encountered (1770 m(3) for fuel elements and 840 m(3) for reflector elements during the lifetime (60 years) of a single reactor module [1]). With the objective to reduce volume of waste in the HTR concept, it is very important to be able to separate the fuel from low level activity graphite. This requires to separate TRISO particles from the graphite matrix with the sine qua non condition to not break TRfSO particles in case of future embedding of particles in a matrix for disposal.According to National Regulatory Systems, in case of limited graphite waste production or of short duration HTR projects (e.g. in Germany), direct disposal without separation is acceptable. Nevertheless, in case or large scale deployment of HTR technology, such approach is not economical and sustainable. Previous attempts in graphite management (furnace, fluidised bed and laser incinerations and encapsulation matrices) dealt with graphite matrix only. These are the reasons why we studied the management of irradiated compact-type fuel element. We simulated the presence of fuel in the particles by using ZrO(2) kernels. Compacts with ZrO(2) TRISO particles were manufactured by AREVA NP.Two original methods have been studied. First, we tested high pressure jet to erode graphite and clean TRISO particles. Best erosion rate reached about 0.18 kg/h for a single nose ending. Examination of treated graphite showed a mixture of undamaged TRISO particles, particles that have lost the outer pyrolytic carbon layer and ZrO(2) kernels. Secondly, we studied the thermal shock method by immerging successively graphite into liquid nitrogen and hot water to cause fracturing of the compact. This produced particles and graphite fragments with diameter ranging from several centimetres to less than 500 mu m. This relatively simple and economic method may potentially be considered as a pretreatment step and be coupled with other method(s) before reprocessing and recycling for example.

The paper introduces a new family of numerical ODE solvers called Quantized State System (QSS) methods. Given a set of ODEs in its state-space representation, the QSS methods replace the classic time slicing by a quantization of the states, leading to an asynchronous discrete-event simulation model instead of a discretetime difference equation model. QSS methods applied to stable linear time-invariant systems give always practically stable numerical results, irrespective of the quantization adopted. Taking into account that the QSS methods are explicit algorithms, this property has strong theoretical implications and offers a promising perspective for applications such as real-time simulation of stiff systems, where implicit solutions are usually unacceptable. Also discussed are the main properties of the methods in the context of simulating discontinuous systems (the asynchronous nature of these algorithms gives them important advantages for discontinuity handling). Another class of systems that can be simulated by means of these algorithms are marginally stable (Hamiltonian) systems.

EOOLT’2007 was the first edition of the ECOOP-EOOLT workshop. The workshop is intended to bring researchers associated with different equation-based object-oriented (EOO) modeling languages and different application areas making use of such languages together. The aim of the workshop is to explore common grounds and derive software design principles that may make future EOO modeling languages more robust, more versatile, and more widely accepted among the various stakeholders. At EOOLT’2007, nineteen researchers with diverse backgrounds and needs came together to present and discuss fourteen different concept papers grouped into the four topic areas of integrated system modeling approaches; hybrid modeling and variable structure systems; modeling languages, specification, and language comparison; and tools and methods.

This paper describes a fault diagnosis system (FDS) for non-linear plants based on fuzzy logic. The proposed scheme, named VisualBlock-FIR, runs under the Simulink framework and enables early fault detection and identification. During fault detection, the FDS should recognize that the plant behavior is abnormal, and therefore, that the plant is not working properly. During fault identification, the FDS should conclude which type of failure has occurred. The enveloping and acceptability measures introduced in VisualBlock-FIR enhance the robustness of the overall process. The final part of this research shows how the proposed approach is used for tackling faults of the DAMADICS benchmark.

This paper deals with two of the main tasks of fault monitoring systems (FMS): fault detection and fault identification. During fault detection, the FMS should recognize that the plant behavior is abnormal, and therefore, that the plant is not working properly. During fault identification, the FMS should conclude which type of failure has occurred. The main goal of this work is to present, in the context of the Fuzzy Inductive Reasoning Fault Monitoring System (FIRFMS), a new fault detection technique called enveloping and an enhancement of the fault identification method based on the model acceptability measure. Both contributions allow a more robust and reliable FIRFMS fault detection and identification processes. The enveloping technique and the model acceptability measure are applied to three applications of quite different areas. The first one corresponds to an electric circuit model previously used for such purpose in the literature. The second one is a biomedical system, the human central nervous system (CNS) control. It is the first attempt to apply the FIRFMS to support medical decisions. The third and last one corresponds to a water demand distribution system. The electric circuit is used to show that the enhanced FIRFMS outperforms the previous FIRFMS. The biomedical and water demand distribution systems are presented to show the good performance of the new FIRFMS.

In the framework of the French V/HTR fuel development and qualification program, the Commissariat a l'Energie Atomique (CEA) and AREVA are conducting R&D projects covering the mastering of UO2 coated particle and fuel compact fabrication technology. To fulfill this task, a review of past knowledge, of existing technologies and a preliminary laboratory-scale work program have been conducted with the aim of retrieving the know-how on HTR coated particle and compact manufacture:The different stages of UO2 kernel fabrication GSP process have been reviewed, reproduced and improved.The experimental conditions for the chemical vapor deposition of coatings have been defined on dummy kernels and development of innovative characterization methods has been carried out.Former CERCA compacting process has been reviewed and updated.In parallel, an experimental manufacturing line for coated particles, named GALA, and a compacting line based on former CERCA compacting experience have been designed, constructed and are in operation since early 2005 at CEA Cadarache and CERCA Romans, respectively. These two facilities constitute the CAPRI line (CEA and AREVA PRoduction Integrated line).The major objectives of the CAPRI line are:to recover and validate past knowledge,to produce representative HTR TRISO fuel meeting industrial standards,to permit the optimization of reference fabrication processes for kernels and coatings defined previously at a laboratory-scale and the investigation of alternative and innovative fuel design (UCO kernel, ZrC coating),to test alternative compact process options andto fabricate and characterize fuel required for irradiation and qualification purpose.This paper presents the status of progress of R&D conducted on HTR fuel particles and compact manufacture by early 2005 and the potential of the laboratory-scale HTR fuel CAPRI line. (c) 2006 Elsevier B.V. All rights reserved.

Continuous-time systems can be converted to discrete- event descriptions using the Quantised State Systems (QSS) formalism. Hence it is possible to simulate continuous-time systems using a discrete-event simu- lation tool, such as a simulation engine based on the DEVS formalism. A new Dymola library, ModelicaDEVS, was devel- oped that implements the DEVS formalism. DEVS has been shown to be efficient for the simu- lation of systems exhibiting frequent switching opera- tions, such asflyback converters. ModelicaDEVS con- tains a number of basic components that can be used to carry out DEVS simulations of physical systems. Furthermore, it is also possible - with some restric- tions - to combine the two simulation types of Mod- elicaDEVS and Dymola (discrete-event and discrete- time simulation) and create hybrid models that contain ModelicaDEVS as well as standard Dymola compo- nents.

Un argumento de reequilibraje del saldo corriente americano - El déficit de la balanza de los pagos corrientes de los Estados Unidos no cesó de incrementarse estos últimos años. El percatarse del carácter más y más preocupante remató a finales del verano de 1985, en una acción coordinada en el plan internacional (acuerdo del Grupó de los Cinco, 22 de septiembre de 1985) teniendo por objeto, en especial, el volver el tipo del dôlar a nivel más normal. De manera a conseguir las condiciones de un reequilibraje de la balanza corriente americana, cierto numéro de simulaciones se llevaron a efecto en el otono de 1985 mediante el modelo multinacional ATLAS. Facilitan una indicación respecto al camino recorrido desde lo que queda por hacer efectivamente. La baja del dólar favorece una reducción del déficit exterior americano, mas no es suficiente. Deberia de estar al minimo, acoplada con una politica presupuestaria restrictiva, destinada a frenar el crecimiento. No obstante, los resultados de esas simulaciones muestran que, sin el apoyo del Japon y de los paises europeos, medidas exclusivamente americanas no serian totalmente eficaces y que ademés serian portadoras de una ralentización patente de la economia mundial. El argumento mes favorable presupone una concertación entre una politica restrictiva llevada a cabo en los Estados Unidos y una politica con miras a apoyar la actividad en Europa y en Japon, ya que éstos aceptan moderar el objetivo de reducción del déficit presupuestario.

The mean shift is a non-parametric algorithm that shifts each sample to the mode of the statistic it belongs to. This filter was originally dedicated to cluster analysis of data and has been recently extended to image processing. In this paper, we are introducing the mean shift algorithm in SAR imagery. It is shown that, after an adapted preprocessing step to reduce the granular aspect of amplitude SAR images, the mean shift gives interesting performances compared to usual SAR parametric filters. This is achieved without any assumptions concerning the underlying statistics involved in the images. An extension of this filter to the coherence image is then proposed. Amplitude and coherence images are simultaneously filtered. It is shown that these two filtered images can be used to improve shadow extraction for building reconstruction.

In the framework of the ANTARES (AREVA New Technology for Advanced Reactor Energy Supply) programme, the Commissariat à l'Energie Atomique (CEA) and AREVA conduct R&D projects covering the mastering of fuel compact fabrication technology with the CAPRI (CEA AREVA PRoduction Integrated) line. Fuel compacts consist of coated particles bonded in a close- packed array by a carbonaceous matrix. This matrix is made by treating a fully graphitized powder (natural graphite and/or needle or pitch coke origin) with a binding agent which is a phenol-formaldehyde resin. The resin bonded matrix has to fulfill a number of essential tasks in the fuel element. Theses tasks are directly influenced by the graphite matrix structure and by the graphite sourcing. A bibliographic review of past irradiation tests performed in the 70's has been done to assess the relationship between graphite matrix materials used and the in pile compact behavior. The goal was to specify compact properties required for the definition of coming SIROCCO irradiation tests in the OSIRIS reactor. This paper presents the results of this bibliographic review. Compact properties leading to acceptable in pile behavior (i.e. dimensional changes, thermal conductivity and coefficient of thermal expansion) are highlighted and the influence of the matrix graphite structure is presented.